201006003 九、發明說明： 【發明所屬之技術領域】 本發明是有關於一種發光二極體’特別是有關於一種可 提高光萃取率之發光二極體。 【先前技術】 近年來，利用含氮化鎵之化合物半導體，如：氮化 鎵（GaN)、氮化鋁鎵（AlGaN)及氮化銦鎵（InGaN)等發光二 ® 極體（Light Emitting Diode)備受矚目。111族化合物係為 一寬能隙材料，其射出光之波長係可從藍光涵蓋至紅 光，幾乎涵蓋所有可見光之波長範圍。此外。相較於傳 統光源，發光二極體具有體積小、壽命長、低電流/電壓 驅動及發光效率佳等優點，因而廣泛應用。 過去，發光二極體主要研究發展重點係在如何提升 内部之量子效應，以提高發光效率。在利用分子束磊晶 (Molecular Beam Epitaxy，MBE)及有機金屬化學氣相沉 ⑩積（Metal-Organic Chemical Vapor Deposition，MOCVD) 等方式提昇磊晶品質後，使内部量子效應與理論值近 似，大幅提升發光效率。但對發光二極體而言，提升内 部發光效率是不足的，必須進一步使光能不被浪費的均 勻射出以符合光源的基本要求。 請參閱第1圖，其係為一習知發光二極體結構示意 圖。具有一基板11、一發光磊晶結構12及一透明窗戶 層13、一 η型歐姆電極14及一 p型歐姆電極15。發光 磊晶結構12係包含一 η型披覆層、一主動層及一 ρ型彼 201006003 覆層，η型歐姆電極14形成於n型披覆層上，p型歐姆 電極15形成p型披覆層上，當外加一電流予p型歐姆電 極時，電流可經由透明窗戶層13均勻擴散至主動層。主 動層產生之光部分經由p型披覆層表面穿過透明窗戶層 13發射出外部，另一部分則可能因全反射原理回到發光 二極體内部，亦可能由透明窗戶層13上之p型歐姆電極 • 15吸收而減低發光二極體之發光效率。故習知係在透明 窗戶層13上開設複數個凹孔131，以增加光線散射之機 ❹率，減少全反射現象，藉以提升發光二極體之亮度。 台灣專利號1296861係揭露一種具有正向光導出結 構之發光二極體，其係於發光二極體之上部表面形成至 ;一正向光導出結構已使光線射出發光二極體之機率增 加以提高發光二極體之發光效率。台灣專利號I29i248 係揭露「種具有多方向性光散射之發光二極體結構及其 製造方法’其係設置—散射層於n型披覆層上此散射 層係具有-散射表面，此散射表面可使發光二極體内部 ❹發出之光發射至外部，藉以達到提高發光二極 效果。 但上述方法所提升之發光效率仍有其限度，無法將 發光二極體之外部發光效率提升至最大，故提升發光二 極體之外部發光效率仍為高亮度發光二極體之主要課 題0 if於習知技藝之各項問題，為了能夠兼顧解決 之，本發1 月人基於多年研究開發與諸多實務經驗，提出 種可提兩光萃取率之發光二極體及其製造方法，以作為 201006003 改善上述缺點之實現方式與依據。 【發明内容】 ^有鑑於此，本發明之目的就是在提供一種可提高光 萃取率之發光二極體，以解決發光二極體外部發光效率 不足之問題。 “根據本發明之目的，提出一種可提高光萃取率之發 f二極體，其包含一基板、一發光磊晶結構及一複合光 ®萃取導電層。發光H结構係形成於基板上，發光二極 體結構係依序由一第一披覆層、一發光層及一第二披覆 層組成。複合光萃取透明導電層係形成於發光磊晶結構 上，此複合光萃取層係由一第一透明導電層及一第二透 明導電層複合形成，此第一透明導電層經由一蝕刻製程 以形成複數個光萃取結構，而後第二透明導電層係覆蓋 於第一透明導電層上。 其中，第二透明導電層上更可覆蓋一透明氧化層以 ❹保護發光二極體，此透明氧化層係可由二氧化矽（Si〇2) 形成。由發光二極體内部光電效應所發出之光射至複合 光萃取導電層，因複合光萃取導電層之折射係數(η)介於 第二坡覆層之折射係數（η)與透明氧化層（Si02)之折射係 數（η)之間，故内部發出之光產生全反射之機率降低， 又’複合光萃取導電層具有複數個光萃取結構，此些光 萃取結構使第二披覆層與複合光萃取導電層之接觸面粗 糙化’如此更降低内部發出之光發生全反射之機率，提 升了發光二極體之亮度。 201006003 效為使貴審查委員對本發明之技術特徵及所達到 之功效有更進一步之瞭解與認識，謹佐以較佳之實施例 及配合詳細之說明如後。 【實施方式】 以下將參照相關圖式，說明依本發明實施例之可提 - 咼光萃取率之發光一極體，為使便於理解，下述實施例中 之相同元件係以相同之符號標示來說明。 ❹ 請參閱第2A圖，其係為本發明之可提高光萃取率 之發光二極體之剖面圖。圖中，可提高光萃取率之發光 二極體係包含一基板21、一發光蠢晶結構22及一複合 光萃取導電層23。基板21係為一藍寶石基板（sapphire)、 石夕（Si)基板或氮化鋁（A1N)基板。發光磊晶結構22係形成 於基板21上，發光磊晶結構22係依序由一第一披覆層 2之1、一發光層222及一第二披覆層223形成，此第一被 覆層221可為一 η型披覆層，第二披覆層223係為〜 ❹ 型披覆層。基板21與發光磊晶結構22之間更可包含^ 緩衝層以利晶格成長。複合光萃取導電層23係形成於^ 光磊晶結構22上，此複合光萃取導電層23包含〜第〜 透明導電層231及一第二透明導電層232,其中，第〜 透明導電層231及該第二透明導電層232係由氧化鋼越 (ΙΤΟ)、氧化錫錫(CTO)、錄/金(Ni/Au)、氧化銀麵/辑 (Agln02/Sn)、氧化辞 /鋁（ZnO: Al; AZO)或氧化鋅鋁（ 形成。第一透明導電層231係與第二披覆層223形成 姆接觸（ohmic contact)，定義複數個區域於第一透明導電 201006003 層231，再經由一姓刻（etching)製程#刻上述區域以形成 複數個光萃取結構233，且此些光萃取、结構233之深度/ 高度係大於λ/4 ，λ係為發光二極體發出之光波長。第 一透明導電層231之折射係數(η)介於第二彼覆層223之 折射係數（η)與透明氧化層（Si〇2)之折射係數(η)之間，故 此些光萃取結構233係可減小第二披覆層223及第一透 明導電層231之間的全反射，藉以減少由發光層222發 出之光的全反射現象。第二透明導電層232係覆蓋於第 一透明導電層231上，第二透明導電層232之折射係數 係可小於或等於第一透明導電層23丨之折射係數以減少 兩者之間的全反射現象，且該複合光萃取透明導電層形 成一不平整表面有助於提高光萃取率。且此第二透明導 電層232係具有低阻抗及高透明度之特性，有助於產生 均勻的電流擴散。第二透明導電層232上更可覆蓋一透 明氧化層27以保護發光二極體，上述透明氧化層27係 為一氧化矽（Si〇2)。透明氧化層27之折射係數係小於第 二透明導電層232之折射係數以減少全反射並提高光萃 取率。發光二極體更可包含一第一電極層25及一第二電 極層26 ’其中’第一電極層25係形成於發光磊晶結構 22上迷與第一彼覆層221形成歐姆接觸（ohmic eontaet) ’第二電極層26係形成於複合光萃取導電層23 上^與其形成歐姆接觸。因第二透明導電層232具有低 阻^之特性’故自第二電極層26注入之電流係經由第二 士 電層232產生均勻的電流擴散（current Sprea(jing) 肌入第〜透明導電層231，又因第一透明導電層與發光 201006003 磊晶結構22兩者係歐姆接觸，故流入第一透明導電層 231之電流亦可傳導至發光蠢晶、结構22，使發光蟲晶結 生光電效應而發光。而後發光蟲晶結構22發出 之光可由光萃取結構233萃取，由第二透明導電層说 發射至外部，因第二透明導電層232具有高透光度之特 性，故可提高發光二極體之外部發光效率。 Ο 清續參閱第2Β目，其係為本發明之可提高光萃取 率之發光二極體之第一實施例俯視圖。圖中，複合光萃 取導電層23係由第—透明導電層及第二透明導電層複 /成。疋義複數個區域於第一透明導電層231上，並 經由蝕刻製程以餘刻此些區域以形成複數個光萃取結 構233，此些光萃取結構233係為一開孔結構。第二透 明導電層係覆蓋於第一透明導電層上，第二透明層係透 過光萃取結構233與第一披覆層部分接觸。當光自發光 層發出時，透過上述接觸之部分可減少光的全反射，以 增加發光二極體發射至外部之光量。第一電極層25係形 成於發光磊晶結構上且與第一披覆層形成歐姆接觸，第 二電極層26係形成於複合光萃取導電層23上且與其形 成歐姆接觸。第一披覆層、第一透明導電層及第二透明 導電層之折射係數(η)係依序遞減少，其中，第二透明導 電層上更可披覆透明氧化層以保護發光二極體不受到物 理因素的損壞，同理，此透明氧化層之折射係數係小於 第二透明導電層之折射係數。藉由上述結構，可減少發 光二極體内部之光消耗量提高發光二極體之亮度，且自 第二電極層26注入之電流係經由複合光萃取導電層23 201006003 產生均勻的電流擴散流入發光磊晶結構，使發光磊晶結 構產生光電效應而發光。 請參閱第2C圖，其係為本發明之可提高光萃取率 之發光二極體之第二實施例之剖面圖。圖中，可提高光 萃取率之發光二極體係包含一基板21、一發光磊晶結構 22及一複合光萃取導電層23’上述基板21係為一藍寶 - 石基板（saPPhire)、矽（Si)基板或氮化鋁（A1N)基板。發光 蠢晶結構22係形成於基板21上，發光蠢晶結構22係由 ® 一第一披覆層221、一發光層222及一第二披覆層223 組成。基板21與發光遙晶結構22之間更可包含一緩衝 層以利晶格成長。複合光萃取導電層23係形成於發光磊 晶結構22上，此複合光萃取導電層23係由一第一透明 導電層231及一第二透明導電層232複合而成，其中， 第一透明導電層231係與第二披覆層223形成歐姆接觸 (ohmic contact)，且第一透明導電層231及該第二透明導 電層232之材料係選自氧化銦錫（ITO)、氧化鎘錫 ❹ （CTO)、鎳/金（Ni/Au)、氧化銀銦/錫（AgIn〇2/Sn)、氧化 鋅/銘（ZnO : Al ; AZO)或氧化鋅鋁（AZO)。定義複數個區 域於第一透明導電層231上，保留此些區域並蝕刻 (etching)其他未定義之區域以形成複數個光萃取結構 233，此些光萃取結構233之深度/高度係大於λ/4，λ係 為發光二極體發出之光波長。再者，第一透明導電層231 之折射係數（η)係小於該第二披覆層223之折射係數，故 此些光萃取結構233係可減小第二披覆層223及第一透 明導電層231之間的全反射，藉以減少由發光層222發 201006003 出之光的全反射現象。第二透明導電層232係覆蓋於第 一透明導電層231上，第二透明導電層232之折射係數 係可小於或等於第一透明導電層231之折射係數以減少 兩者之間的全反射現象，且第二透明導電層232亦具有 低阻抗及高透明度之特性。第二透明導電層232上更可 覆蓋一透明氧化層27，如同上述，此透明氧化層27之 . 折射係數須小於第二透明導電層232之折射係數以提高 發光二極體之亮度，此透明氧化層27保護發光二極體並 ❿ 提高光萃取率。此透明氧化層27係為二氧化矽（Si02)。 發光二極體更可包含一第一電極層25及一第二電極層 26,其中，第一電極層25係形成於發光磊晶結構22上， 並與第一披覆層221形成歐姆接觸，第二電極層26係形 成於複合光萃取導電層23上並與其形成歐姆接觸。因第 二透明導電層232具有低阻抗之特性，故自第二電極層 26注入之電流係經由第二透明導電層232產生均勻的電 流擴散（current spreading)流入第一透明導電層231，又 ❹ 因第一透明導電層231所形成之光萃取結構233與發光 磊晶結構22形成歐姆接觸，故流入第一透明導電層231 之電流亦可傳導至發光磊晶結構22,使發光磊晶結構22 產生光電效應而發光。而後發光磊晶結構22發出之光可 由光萃取結構233萃取，由第二透明導電層232發射至 外部，因第二透明導電層232具有高透光度之特性，故 可提高發光二極體之外部發光效率。 請續參閱第2D圖，其係為本發明之可提高光萃取 率之發光二極體之第二實施例之俯視圖。圖中，複合光 12 201006003 萃取導電層23係由第一透明導電層及第二透明導電層 複合形成。定義複數個區域於第一透明導電層231上， 保留此些區域並餘刻（etching)其他未定義之區域以形成 複數個光萃取結構233，此些光萃取結構233之深度/高 度係大於λ/4，λ係為發光二極體發出之光波長。第二透 明導電層係覆蓋於第一透明導電層上，第二透明層係透 - 過已蝕刻之區域與第一披覆層部分接觸，當光自發光層 、 發出時，透過上述接觸之部分可減少光的全反射，以增 〇 加發光二極體發射至外部之光量。第一電極層25係形成 於發光磊晶結構上且與第一披覆層形成歐姆接觸，第二 電極層26係形成於複合光萃取導電層23上且與其形成 歐姆接觸。第一披覆層、第一透明導電層及第二透明導 電層之折射係數(η)係依序遞減少，其中’第二透明導電 層上更可披覆透明氧化層以保護發光二極體不受到物理 因素的損壞，同理，此透明氧化層之折射係數係小於第 一透明導電層之折射係數。藉由上述結構，可減少發光 ❹二極體内部之光消耗量提高發光二極體之亮度。第二透 明導電層係具有低阻抗及高透明度之特性，故自第二電 極層26注入之電流係由第二透明導電層產生均勻的電 流擴散效果流入第一透明導電層。因第一透明導電層形 成之光萃取結構233係與第二披覆層形成歐姆接觸，故 第二透明導電層流入之電流係藉由光萃取結構233流入 發光磊晶結構，使發光磊晶結構產生光電效應而發光。 而後發光磊晶結構發出之光亦可由光萃取結構233有效 萃取’利用具有高透明度之第二透明導電層發散至外 13 201006003 部，提高發光二極體之外部發光效率。 請參閱第3A圖，其係為本發明之可提高光萃取率 之發光一極體之第二實施例之剖面圖。圖中，可提高光 萃取率之發光二極體係包含一基板31、一發光蟲晶結構 32及一複合光萃取導電層33’其中，基板31係為一砷 化嫁（GaAs)基板。發光蠢晶結構32係包^ —第一坡覆層 . 321、依發光層322及一第二披覆層323。複合光萃取導 電層33係形成於發光蠢晶結構32上，此複合光萃取導 〇 電層33包含一第一透明導電層331及一第二透明導電層 332,其中，第一透明導電層331及該第二透明導電層 332係由氧化銦錫（ITO)、氧化鎘錫（CTO)、鎳/金(Ni/Au)、 氧化銀銦/錫（Agln02/Sn)、氧化鋅/鋁（ZnO : Al ; AZO) 或氧化鋅鋁（AZO)形成。第一透明導電層331係與第二 披覆層323形成歐姆接觸（ohmic contact)。定義複數個區 域於第一透明導電層331上，再經由一餘刻（etching)製 程蝕刻上述區域以形成複數個光萃取結構333,且此些 ❹ 光萃取結構333之深度/高度係大於λ/4, λ係為發光二極 體發出之光波長。第一透明導電層331之折射係數(η)係 小於該第二披覆層323之折射係數，故此些光萃取結構 333係可減小第二披覆層323及第一透明導電層331之 間的全反射，藉以減少由發光層222發出之光的全反射 現象。第二透明導電層332係覆蓋於第一透明導電層331 上，且第二透明導電層332之折射係數係可小於或等於 第一透明導電層331之折射係數以減少兩者之間的全反 射現象，且此第二透明導電層332係具有低阻抗及高透 201006003 明度之特性。第二透明導電層332上更可覆蓋一透明氧 化層37以保護發光二極體，此透明氧化層27係為二氧 化矽（Si02)。上述透明氧化層37之折射係數係小於第二 透明導電層332之折射係數以減低全反射，達到提高光 萃取率之效果。發光二極體更可包含一第一電極層35 及一第二電極層36，其中，第一電極層35係形成於基 . 板31下，並位於緩衝層34之相對侧邊，第二電極層36 係形成於複合光萃取導電層33上並與其形成歐姆接 ❹ 觸。自第二電極層36注入之電流係經由第二透明導電層 332產生均勻的電流擴散（current spreading)流入第一透 明導電層331，又因第一透明導電層331與發光磊晶結 構32兩者係歐姆接觸，故流入第一透明導電層331之電 流亦可傳導至發光磊晶結構32。再者，第二透明導電層 332具有高透光度之特性，故發光磊晶結構32發出之光 經由光萃取結構333萃取，可自第二透明導電層332發 射至外部。 © 請參閱第3B圖，其係為本發明之可提高光萃取率 之發光二極體之第三實施例之俯視圖。圖中，複合光萃 取導電層33係由第一透明導電層及第二透明導電層複 合形成。定義複數個區域於第一透明導電層331上，並 經由一蝕刻製程以蝕刻此些區域以形成複數個光萃取結 構333，此些光萃取結構333係為一開孔結構。第二透 明導電層係覆蓋於第一透明導電層上，第二透明層係透 過光萃取結構333與第一披覆層部分接觸，當光自發光 層發出時，透過上述接觸之部分可減少光的全反射，以 15 201006003 增加發光二極體發射至外部之光量。第一披覆層、第一 透明導電層及第二透明導電層之折射係數（n)係依序遞 減少。藉由上述結構’可減少發光二極體各半導體層之 間的全反射現象，減少内部之光消耗量以提高發光二極 體之亮度’且自第二電極層36注入之電流係經由複合光 萃取導電層33產生均勻的電流擴散流入發光磊晶結 構’使發光磊晶結構產生光電效應而發光。 請參閱第3C圖’其係為本發明之可提高光萃取率 ® 之發光二極體之第四實施例之剖面圖。圖中’提高光萃 取率之發光二極體係包含一基板31、一發光磊晶結構32 及一複合光萃取導電層33，其中，基板31係為一神化 鎵（GaAs)基板。發光磊晶結構32係包含一第一披覆層 321、一發光層322及一第二披覆層323。複合光萃取導 電層33係形成於發光磊晶結構32上，此複合光萃取導 電層33包含一第一透明導電層331及一第二透明導電層 332。且第二透明導電層332之折射係數係可小於或等於 ❹ 第一透明導電層331之折射係數以減少兩者之間的全反 射現象，且此第二透明導電層332係具有低阻抗及高透 明度之特性。第二透明導電層332上更可覆蓋一透明氧 化層37以保護發光二極體’此透明氧化層27係為二氧 化梦（Si〇2)。上述透明氧化層37之折射係數係小於第二 透明導電層332之折射係數以減低全反射，達到提高光 萃取率之效果。發光二極體更可包含一第一電極層35 及一第二電極層36，其中，第一電極層35係形成於基 板31下’並位於緩衝層34之相對側邊，第二電極層％ 201006003 係形成於複合光萃取導電層33上並與其形成歐姆接 觸。自第二電極層36注入之電流係經由第二透明導電層 332產生均勻的電流擴散（current spreading)流入第一透 明導電層331，又因第一透明導電層331與發光磊晶結 構32兩者係歐姆接觸，故流入第一透明導電層331之電 流亦可傳導至發光磊晶結構32。再者，第二透明導電層 332具有高透光度之特性，故發光磊晶結構32發出之光 經由光萃取結構333萃取，可自第二透明導電層332發 © 射至外部。 請續參閱第3D圖，其係為本發明之可提高光萃取 率之發光二極體之第四實施例之俯視圖。複合光萃取導 電層23係由第一透明導電層及第二透明導電層複合形 成。定義複數個區域於第一透明導電層331上，而後保 留此些區域並餘刻（etching)其他未定義之區域以形成複 數個光萃取結構333，此些光萃取結構333之深度/高度 係大於λ/4，λ係為發光二極體發出之光波長。第二透明 G 導電層係覆蓋於第一透明導電層上，第二透明層係透過 已蝕刻之區域與第一披覆層部分接觸，當光自發光層發 出時，透過上述接觸之部分可減少光的全反射，以增加 發光二極體發射至外部之光量。第一電極層25係形成於 發光磊晶結構上且與第一彼覆層形成歐姆接觸，第二電 極層36係形成於複合光萃取導電層33上且與複合光萃 取導電層33形成歐姆接觸。第一披覆層、第一透明導電 層及第二透明導電層之折射係數（η)係依序遞減少，其 中，第二透明導電層上更可彼覆透明氧化層以保護發光 17 201006003 二極體不受到物理因素的損壞，同理，此透明氧化層之 折射係數係小於第二透明導電層之折射係數。藉由上述 結構，可減少各半導體層間全反射之現象，並減少發光 一極體内部之光消耗量以提高發光二極體之亮度。第二 透明導電層係具有低阻抗之特性，故自第二電極層36 注入之電流係由第二透明導電層產生均勻的電流擴散效 果流入第一透明導電層。因第一透明導電層形成之光萃 取結構333係與第二披覆層形成歐姆接觸，故第二透明 導電層流入之電流係藉由光萃取結構333流入發光磊晶 結構，使發光磊晶結構產生光電效應而發光。而後發光 磊晶結構發出之光亦可由光萃取結構333有效萃取，並 利用具有高透明度之第二透明導電層發散至外部，提高 發光二極體之外部發光效率。 以上所述僅為舉例性，而非為限制性者。任何未脫 離本發明之精神與範疇，而對其進行之等效修改或變 ❹更，均應包含於後附之申請專利範圍中。 【圖式簡單說明】 第1圖係為習知發光二極體結構示意圖； 第2A圖係為本發明之可提高光萃取率之發光二極體之 第一實施例剖面圖； 第2B圖係為本發明之可提高光萃取率之發光二極體之 第一實施例俯視圖； 第c圖係、為本發明之可提高光萃取率之發光二極體之 第二實施例之剖面圖； 18 Μ 201006003 第2D圖係為本發明之可提高光萃取率之發光二極體之 第二實施例之俯視圖； 第3Α圖係為本發明之可提高光萃取率之發光二極體之 第三實施例之剖面圖； 第3Β圖係為本發明之可提高光萃取率之發光二極體之 第三實施例之俯視圖； 第3C圖係為本發明之可提高光萃取率之發光二極體之 Ο 第四實施例之剖面圖；以及 第3D圖係為本發明之可提高光萃取率之發光二極體之 第四實施例之俯視圖。 【主要元件符號說明】 11 :基板； 12 ·發光遙晶結構； 13 :透明窗戶層； 131 :凹孔； ϋ 14 : η型歐姆電極； I5 : ρ型歐姆電極； 21 :基板； 22 :發光蟲晶結構； 221 :第一坡覆層； 222 :發光層； 223 :第二披覆層； 23 :複合光萃取導電層； 231 :第一透明導電層； 19 201006003 232 :第二透明導電層； 233 :光萃取結構； 24 :緩衝層； 25 :第一電極層； 26 :第二電極層； 27 :透明氧化層； 31 :基板； 3 2 ·發光蠢晶結構， 321 :第一彼覆層； 322 :發光層； 323 :第二披覆層； 33 :複合光萃取導電層； 331 :第一透明導電層； 332 :第二透明導電層； 333 :光萃取結構； 34 :緩衝層； 35 :第一電極層； 36 :第二電極層；以及 37 ··透明氧化層。201006003 IX. Description of the Invention: [Technical Field] The present invention relates to a light-emitting diode, and particularly relates to a light-emitting diode which can improve light extraction rate. [Prior Art] In recent years, gallium nitride-based compound semiconductors such as gallium nitride (GaN), aluminum gallium nitride (AlGaN), and indium gallium nitride (InGaN) have been used as Light Emitting Diodes. ) is highly regarded. The Group 111 compound is a wide bandgap material that emits light at wavelengths ranging from blue to red, covering almost all wavelength ranges of visible light. Also. Compared with the conventional light source, the light-emitting diode has the advantages of small volume, long life, low current/voltage driving, and good luminous efficiency, and thus is widely used. In the past, the main research and development focus of LEDs was on how to enhance the internal quantum effects to improve luminous efficiency. After using the Molecular Beam Epitaxy (MBE) and the Metal-Organic Chemical Vapor Deposition (MOCVD) method to improve the epitaxial quality, the internal quantum effect is approximated by the theoretical value. Improve luminous efficiency. However, for the light-emitting diode, it is insufficient to improve the internal luminous efficiency, and it is necessary to further uniformly emit the light energy without being wasted to meet the basic requirements of the light source. Please refer to Fig. 1, which is a schematic diagram of a conventional light-emitting diode structure. There is a substrate 11, a light emitting epitaxial structure 12 and a transparent window layer 13, an n-type ohmic electrode 14, and a p-type ohmic electrode 15. The luminescent epitaxial structure 12 comprises an n-type cladding layer, an active layer and a p-type 201006003 cladding layer, the n-type ohmic electrode 14 is formed on the n-type cladding layer, and the p-type ohmic electrode 15 forms a p-type cladding layer. On the layer, when a current is applied to the p-type ohmic electrode, current can be uniformly diffused to the active layer via the transparent window layer 13. The light generated by the active layer is partially emitted through the transparent window layer 13 via the surface of the p-type cladding layer, and the other portion may return to the inside of the light-emitting diode due to the principle of total reflection, or may be p-type on the transparent window layer 13. The ohmic electrode • 15 absorbs and reduces the luminous efficiency of the light-emitting diode. Therefore, it is customary to open a plurality of recessed holes 131 in the transparent window layer 13 to increase the probability of light scattering and reduce the total reflection phenomenon, thereby improving the brightness of the light-emitting diode. Taiwan Patent No. 1296861 discloses a light-emitting diode having a forward light-extracting structure formed on the upper surface of the light-emitting diode; a positive light-extracting structure has increased the probability of light emitting the light-emitting diode Improve the luminous efficiency of the light-emitting diode. Taiwan Patent No. I29i248 discloses "a light-emitting diode structure having multi-directional light scattering and a method for fabricating the same". The system is provided with a scattering layer on the n-type cladding layer. The scattering layer has a scattering surface, and the scattering surface The light emitted from the inside of the light-emitting diode can be emitted to the outside, thereby improving the effect of the light-emitting diode. However, the luminous efficiency improved by the above method still has a limit, and the external light-emitting efficiency of the light-emitting diode cannot be maximized. Therefore, the external light-emitting efficiency of the light-emitting diode is still the main subject of the high-brightness light-emitting diode. 0 If the problem of the conventional skill is solved, in order to solve the problem, the person in January is based on years of research and development and many practices. Experience, a light-emitting diode capable of extracting two light extraction rates and a manufacturing method thereof are proposed as an implementation and basis for improving the above disadvantages as 201006003. [Invention] In view of the above, the object of the present invention is to provide a A light-emitting diode that increases the light extraction rate to solve the problem of insufficient external luminous efficiency of the light-emitting diode. "In accordance with the purpose of the present invention, A f-polarizer capable of improving light extraction rate comprises a substrate, a luminescent epitaxial structure and a composite light-extracting conductive layer. The light-emitting H structure is formed on the substrate, and the light-emitting diode structure is sequentially composed of a first cladding layer, a light-emitting layer and a second cladding layer. The composite light extraction transparent conductive layer is formed on the luminescent epitaxial structure, and the composite light extraction layer is formed by a first transparent conductive layer and a second transparent conductive layer, and the first transparent conductive layer is formed through an etching process. A plurality of light extraction structures, and then the second transparent conductive layer covers the first transparent conductive layer. Wherein, the second transparent conductive layer may further cover a transparent oxide layer to protect the light emitting diode, and the transparent oxide layer may be formed by cerium oxide (Si〇2). The light emitted by the internal photoelectric effect of the light-emitting diode is incident on the composite light extraction conductive layer, because the refractive index (η) of the composite light extraction conductive layer is between the refractive index (η) of the second slope layer and the transparent oxide layer ( Between Si2), the refractive index (η) is reduced, so that the internal light emission has a reduced probability of total reflection, and the 'composite light extraction conductive layer has a plurality of light extraction structures, and the light extraction structures make the second cladding layer and composite The roughening of the contact surface of the light extraction conductive layer is such that the probability of total reflection of the internally emitted light is reduced, and the brightness of the light emitting diode is improved. 201006003 The following is a further understanding and understanding of the technical features and the efficacies of the present invention. [Embodiment] Hereinafter, a light-emitting diode of a light-extractable extraction rate according to an embodiment of the present invention will be described with reference to the related drawings. For ease of understanding, the same components in the following embodiments are denoted by the same symbols. To illustrate. ❹ Refer to Fig. 2A, which is a cross-sectional view of the light-emitting diode of the present invention which can improve the light extraction rate. In the figure, the light-emitting diode system which can improve the light extraction rate comprises a substrate 21, a light-emitting amorphous structure 22 and a composite light-extracting conductive layer 23. The substrate 21 is a sapphire, a Si (Si) substrate or an aluminum nitride (A1N) substrate. The luminescent epitaxial structure 22 is formed on the substrate 21, and the luminescent epitaxial structure 22 is sequentially formed by a first cladding layer 2, a luminescent layer 222 and a second cladding layer 223. The first cladding layer is formed. 221 may be an n-type cladding layer, and the second cladding layer 223 may be a ~-type cladding layer. A buffer layer may be further included between the substrate 21 and the luminescent epitaxial structure 22 to facilitate lattice growth. The composite light extraction conductive layer 23 is formed on the optical epitaxial structure 22, and the composite light extraction conductive layer 23 includes a first transparent conductive layer 231 and a second transparent conductive layer 232, wherein the first transparent conductive layer 231 and The second transparent conductive layer 232 is made of oxidized steel (ΙΤΟ), tin tin oxide (CTO), recorded/gold (Ni/Au), silver oxide surface/series (Agln02/Sn), and oxidized/aluminum (ZnO: Al; AZO) or zinc aluminum oxide (formed. The first transparent conductive layer 231 forms an ohmic contact with the second cladding layer 223, defines a plurality of regions on the first transparent conductive layer 201006003 layer 231, and then passes through a last name The etching process #scribes the above regions to form a plurality of light extraction structures 233, and the depth/height of the light extraction and structures 233 is greater than λ/4, and the λ is the wavelength of light emitted by the light-emitting diodes. The refractive index (η) of the transparent conductive layer 231 is between the refractive index (η) of the second partial layer 223 and the refractive index (η) of the transparent oxide layer (Si〇2), so the light extraction structures 233 can be Reducing total reflection between the second cladding layer 223 and the first transparent conductive layer 231, thereby reducing the light-emitting layer 2 The total reflection phenomenon of the emitted light is 22. The second transparent conductive layer 232 is covered on the first transparent conductive layer 231, and the refractive index of the second transparent conductive layer 232 is less than or equal to the refractive index of the first transparent conductive layer 23 In order to reduce the total reflection between the two, and the composite light extraction of the transparent conductive layer to form an uneven surface helps to improve the light extraction rate, and the second transparent conductive layer 232 has the characteristics of low impedance and high transparency. The transparent conductive layer 232 is further covered with a transparent oxide layer 27 to protect the light-emitting diodes, and the transparent oxide layer 27 is yttrium oxide (Si〇2). The refractive index of 27 is smaller than the refractive index of the second transparent conductive layer 232 to reduce total reflection and increase the light extraction rate. The light emitting diode may further include a first electrode layer 25 and a second electrode layer 26 'the first The electrode layer 25 is formed on the luminescent epitaxial structure 22 to form an ohmic contact with the first cladding layer 221. The second electrode layer 26 is formed on the composite light extraction conductive layer 23 to form an ohmic portion thereof. Since the second transparent conductive layer 232 has a low resistance characteristic, the current injected from the second electrode layer 26 generates uniform current diffusion through the second electric layer 232 (current Sprea (jing) muscle in the first to transparent The conductive layer 231 is in ohmic contact with the first transparent conductive layer and the illuminating 201006003 epitaxial structure 22, so that the current flowing into the first transparent conductive layer 231 can also be conducted to the luminescent crystal, the structure 22, and the luminescent crystal is crystallized. It emits light by photoelectric effect. Then, the light emitted by the luminescent crystal structure 22 can be extracted by the light extraction structure 233, and emitted by the second transparent conductive layer to the outside. Since the second transparent conductive layer 232 has high transmittance, the light emitting diode can be improved. External luminous efficiency. Ο Refer to the second item, which is a plan view of the first embodiment of the light-emitting diode of the present invention which can improve the light extraction rate. In the figure, the composite light extraction conductive layer 23 is formed by the first transparent conductive layer and the second transparent conductive layer. A plurality of regions are disposed on the first transparent conductive layer 231, and are etched through the etching process to form a plurality of light extraction structures 233, which are an open-cell structure. The second transparent conductive layer covers the first transparent conductive layer, and the second transparent layer is in contact with the first cladding layer portion through the light extraction structure 233. When light is emitted from the light-emitting layer, the total reflection of light is reduced by the portion of the contact to increase the amount of light emitted from the light-emitting diode to the outside. The first electrode layer 25 is formed on the luminescent epitaxial structure and forms an ohmic contact with the first cladding layer, and the second electrode layer 26 is formed on the composite light extraction conductive layer 23 and forms an ohmic contact therewith. The refractive index (η) of the first cladding layer, the first transparent conductive layer and the second transparent conductive layer are sequentially decreased, wherein the second transparent conductive layer is further covered with a transparent oxide layer to protect the light emitting diode Without being damaged by physical factors, the refractive index of the transparent oxide layer is smaller than the refractive index of the second transparent conductive layer. With the above configuration, the light consumption inside the light-emitting diode can be reduced to increase the brightness of the light-emitting diode, and the current injected from the second electrode layer 26 is generated by the composite light extraction conductive layer 23 201006003 to generate uniform current diffusion into the light. The epitaxial structure causes the luminescent epitaxial structure to produce a photoelectric effect and emit light. Referring to Fig. 2C, which is a cross-sectional view showing a second embodiment of the light-emitting diode of the present invention which can improve the light extraction rate. In the figure, the light-emitting diode system capable of improving the light extraction rate comprises a substrate 21, a light-emitting epitaxial structure 22 and a composite light-extracting conductive layer 23'. The substrate 21 is a sapphire-stone substrate (saPPhire), 矽 ( Si) substrate or aluminum nitride (A1N) substrate. The light emitting structure 22 is formed on the substrate 21, and the light emitting structure 22 is composed of a first cladding layer 221, a light emitting layer 222, and a second cladding layer 223. A buffer layer may be further included between the substrate 21 and the luminescent crystal structure 22 to facilitate lattice growth. The composite light extraction conductive layer 23 is formed on the luminescent epitaxial structure 22, and the composite light extraction conductive layer 23 is formed by combining a first transparent conductive layer 231 and a second transparent conductive layer 232, wherein the first transparent conductive layer The layer 231 is formed into an ohmic contact with the second cladding layer 223, and the materials of the first transparent conductive layer 231 and the second transparent conductive layer 232 are selected from indium tin oxide (ITO) and cadmium tin oxide. CTO), nickel/gold (Ni/Au), silver indium/tin (AgIn〇2/Sn), zinc oxide/Ming (ZnO: Al; AZO) or zinc aluminum oxide (AZO). Defining a plurality of regions on the first transparent conductive layer 231, leaving the regions and etching other undefined regions to form a plurality of light extraction structures 233, the depth/height of the light extraction structures 233 being greater than λ/4 λ is the wavelength of light emitted by the light-emitting diode. Furthermore, the refractive index (η) of the first transparent conductive layer 231 is smaller than the refractive index of the second cladding layer 223, so the light extraction structures 233 can reduce the second cladding layer 223 and the first transparent conductive layer. Total reflection between 231, in order to reduce the total reflection of the light emitted by the light-emitting layer 222 201006003. The second transparent conductive layer 232 covers the first transparent conductive layer 231, and the refractive index of the second transparent conductive layer 232 can be less than or equal to the refractive index of the first transparent conductive layer 231 to reduce the total reflection between the two. And the second transparent conductive layer 232 also has the characteristics of low impedance and high transparency. The second transparent conductive layer 232 may further cover a transparent oxide layer 27. As described above, the refractive index of the transparent oxide layer 27 must be smaller than the refractive index of the second transparent conductive layer 232 to improve the brightness of the light-emitting diode. The oxide layer 27 protects the light-emitting diode and increases the light extraction rate. This transparent oxide layer 27 is cerium oxide (SiO 2 ). The light emitting diode may further include a first electrode layer 25 and a second electrode layer 26, wherein the first electrode layer 25 is formed on the light emitting epitaxial structure 22 and forms an ohmic contact with the first cladding layer 221, The second electrode layer 26 is formed on the composite light extraction conductive layer 23 and forms an ohmic contact therewith. Since the second transparent conductive layer 232 has a low impedance characteristic, the current injected from the second electrode layer 26 generates uniform current spreading through the second transparent conductive layer 232 to flow into the first transparent conductive layer 231, and Since the light extraction structure 233 formed by the first transparent conductive layer 231 forms an ohmic contact with the light emitting epitaxial structure 22, the current flowing into the first transparent conductive layer 231 can also be conducted to the light emitting epitaxial structure 22, so that the light emitting epitaxial structure 22 It produces a photoelectric effect and emits light. The light emitted by the luminescent epitaxial structure 22 can be extracted by the light extraction structure 233 and emitted from the second transparent conductive layer 232 to the outside. Since the second transparent conductive layer 232 has high transmittance, the light emitting diode can be improved. External luminous efficiency. Please refer to FIG. 2D, which is a plan view of a second embodiment of the light-emitting diode of the present invention which can improve the light extraction rate. In the figure, composite light 12 201006003 The extraction conductive layer 23 is formed by combining a first transparent conductive layer and a second transparent conductive layer. Defining a plurality of regions on the first transparent conductive layer 231, retaining the regions and etching other undefined regions to form a plurality of light extraction structures 233, the depth/height of the light extraction structures 233 being greater than λ/ 4. λ is the wavelength of light emitted by the light-emitting diode. The second transparent conductive layer covers the first transparent conductive layer, and the second transparent layer passes through the etched region and is in contact with the first cladding layer portion. When the light is emitted from the light emitting layer, the portion passing through the contact portion The total reflection of light can be reduced to increase the amount of light emitted by the light-emitting diode to the outside. The first electrode layer 25 is formed on the luminescent epitaxial structure and forms an ohmic contact with the first cladding layer, and the second electrode layer 26 is formed on the composite light extraction conductive layer 23 and forms an ohmic contact therewith. The refractive index (η) of the first cladding layer, the first transparent conductive layer and the second transparent conductive layer is sequentially decreased, wherein the second transparent conductive layer is further covered with a transparent oxide layer to protect the light emitting diode Without being damaged by physical factors, the refractive index of the transparent oxide layer is smaller than the refractive index of the first transparent conductive layer. According to the above configuration, the amount of light consumed inside the light-emitting diode can be reduced to increase the brightness of the light-emitting diode. The second transparent conductive layer has the characteristics of low impedance and high transparency, so that the current injected from the second electrode layer 26 is generated by the second transparent conductive layer to generate a uniform current diffusion effect into the first transparent conductive layer. Since the light extraction structure 233 formed by the first transparent conductive layer forms an ohmic contact with the second cladding layer, the current flowing in the second transparent conductive layer flows into the luminescent epitaxial structure through the light extraction structure 233, so that the luminescent epitaxial structure is formed. It produces a photoelectric effect and emits light. Then, the light emitted by the luminescent epitaxial structure can also be effectively extracted by the light extraction structure 233, and the second transparent conductive layer having high transparency is used to diverge to the outer portion of the 2010-06003 portion, thereby improving the external luminous efficiency of the light emitting diode. Referring to Fig. 3A, which is a cross-sectional view showing a second embodiment of the light-emitting diode of the present invention which can improve the light extraction rate. In the figure, the light-emitting diode system capable of improving the light extraction rate comprises a substrate 31, a luminescent crystal structure 32 and a composite light extraction conductive layer 33', wherein the substrate 31 is an arsenide (GaAs) substrate. The light-emitting abrupt crystal structure 32 is a first slope coating layer 321 , a light-emitting layer 322 and a second cladding layer 323. The composite light extraction conductive layer 33 is formed on the light emitting structure 32. The composite light extraction conductive layer 33 includes a first transparent conductive layer 331 and a second transparent conductive layer 332, wherein the first transparent conductive layer 331 And the second transparent conductive layer 332 is made of indium tin oxide (ITO), cadmium tin oxide (CTO), nickel/gold (Ni/Au), silver indium/tin (Agln02/Sn), zinc oxide/aluminum (ZnO). : Al ; AZO) or zinc aluminum oxide (AZO). The first transparent conductive layer 331 forms an ohmic contact with the second cladding layer 323. A plurality of regions are defined on the first transparent conductive layer 331, and the regions are etched through an etching process to form a plurality of light extraction structures 333, and the depth/height of the light extraction structures 333 is greater than λ/ 4. The λ system is the wavelength of light emitted by the light-emitting diode. The refractive index (η) of the first transparent conductive layer 331 is smaller than the refractive index of the second cladding layer 323. Therefore, the light extraction structures 333 can reduce the relationship between the second cladding layer 323 and the first transparent conductive layer 331. Total reflection, thereby reducing the total reflection of light emitted by the luminescent layer 222. The second transparent conductive layer 332 covers the first transparent conductive layer 331 , and the refractive index of the second transparent conductive layer 332 can be less than or equal to the refractive index of the first transparent conductive layer 331 to reduce total reflection between the two. Phenomenon, and the second transparent conductive layer 332 has the characteristics of low impedance and high transmittance of 201006003. The second transparent conductive layer 332 is further covered with a transparent oxide layer 37 to protect the light-emitting diodes. The transparent oxide layer 27 is tantalum dioxide (SiO 2 ). The refractive index of the transparent oxide layer 37 is smaller than the refractive index of the second transparent conductive layer 332 to reduce total reflection, thereby achieving an effect of improving the light extraction rate. The light emitting diode may further include a first electrode layer 35 and a second electrode layer 36, wherein the first electrode layer 35 is formed under the base plate 31 and located on opposite sides of the buffer layer 34, and the second electrode Layer 36 is formed on the composite light extraction conductive layer 33 and forms an ohmic contact with it. The current injected from the second electrode layer 36 is generated by the second transparent conductive layer 332 to generate uniform current spreading into the first transparent conductive layer 331 and by the first transparent conductive layer 331 and the luminescent epitaxial structure 32. Because of the ohmic contact, the current flowing into the first transparent conductive layer 331 can also be conducted to the luminescent epitaxial structure 32. Furthermore, the second transparent conductive layer 332 has a high transmittance characteristic, so that the light emitted from the luminescent epitaxial structure 32 is extracted through the light extraction structure 333 and can be emitted from the second transparent conductive layer 332 to the outside. © Refer to Fig. 3B, which is a plan view of a third embodiment of the light-emitting diode of the present invention which can improve the light extraction rate. In the figure, the composite light extraction conductive layer 33 is formed by a combination of a first transparent conductive layer and a second transparent conductive layer. A plurality of regions are defined on the first transparent conductive layer 331 and etched through an etching process to form a plurality of light extraction structures 333, the light extraction structures 333 being an open cell structure. The second transparent conductive layer covers the first transparent conductive layer, and the second transparent layer is in contact with the first cladding layer through the light extraction structure 333. When the light is emitted from the light emitting layer, the light is reduced through the contact portion. The total reflection, to 15 201006003 increases the amount of light emitted by the light-emitting diode to the outside. The refractive index (n) of the first cladding layer, the first transparent conductive layer and the second transparent conductive layer is sequentially decreased. With the above structure, the total reflection phenomenon between the semiconductor layers of the light-emitting diode can be reduced, the internal light consumption can be reduced to increase the brightness of the light-emitting diode, and the current injected from the second electrode layer 36 can be passed through the composite light. The extraction of the conductive layer 33 produces a uniform current diffusion into the luminescent epitaxial structure, which causes the luminescent epitaxial structure to produce a photoelectric effect and emit light. Please refer to FIG. 3C' for a cross-sectional view of a fourth embodiment of the light-emitting diode of the present invention which can improve the light extraction rate. In the figure, the light-emitting diode system for increasing the light extraction rate comprises a substrate 31, a light-emitting epitaxial structure 32 and a composite light-extracting conductive layer 33, wherein the substrate 31 is a gallium (GaAs) substrate. The luminescent epitaxial structure 32 includes a first cladding layer 321 , a luminescent layer 322 , and a second cladding layer 323 . The composite light extraction conductive layer 33 is formed on the luminescent epitaxial structure 32. The composite light extraction conductive layer 33 includes a first transparent conductive layer 331 and a second transparent conductive layer 332. The refractive index of the second transparent conductive layer 332 can be less than or equal to the refractive index of the first transparent conductive layer 331 to reduce the total reflection between the two, and the second transparent conductive layer 332 has low impedance and high The nature of transparency. The second transparent conductive layer 332 may further cover a transparent oxide layer 37 to protect the light-emitting diodes. The transparent oxide layer 27 is a dioxide dream (Si〇2). The refractive index of the transparent oxide layer 37 is smaller than the refractive index of the second transparent conductive layer 332 to reduce total reflection, thereby achieving an effect of improving the light extraction rate. The light emitting diode may further include a first electrode layer 35 and a second electrode layer 36, wherein the first electrode layer 35 is formed under the substrate 31 and located on opposite sides of the buffer layer 34, and the second electrode layer% 201006003 is formed on the composite light extraction conductive layer 33 and forms an ohmic contact therewith. The current injected from the second electrode layer 36 is generated by the second transparent conductive layer 332 to generate uniform current spreading into the first transparent conductive layer 331 and by the first transparent conductive layer 331 and the luminescent epitaxial structure 32. Because of the ohmic contact, the current flowing into the first transparent conductive layer 331 can also be conducted to the luminescent epitaxial structure 32. Furthermore, the second transparent conductive layer 332 has a high transmittance characteristic, so that the light emitted from the luminescent epitaxial structure 32 is extracted through the light extraction structure 333, and can be emitted from the second transparent conductive layer 332 to the outside. Please refer to FIG. 3D, which is a plan view of a fourth embodiment of the light-emitting diode of the present invention which can improve the light extraction rate. The composite light extraction conductive layer 23 is formed by a composite of a first transparent conductive layer and a second transparent conductive layer. Defining a plurality of regions on the first transparent conductive layer 331, and then retaining the regions and etching other undefined regions to form a plurality of light extraction structures 333, the depth/height of the light extraction structures 333 being greater than λ /4, λ is the wavelength of light emitted by the light-emitting diode. The second transparent G conductive layer covers the first transparent conductive layer, and the second transparent layer is in contact with the first cladding layer through the etched region. When the light is emitted from the light emitting layer, the portion passing through the contact can be reduced. Total reflection of light to increase the amount of light emitted by the light-emitting diode to the outside. The first electrode layer 25 is formed on the luminescent epitaxial structure and forms an ohmic contact with the first cladding layer, and the second electrode layer 36 is formed on the composite light extraction conductive layer 33 and forms an ohmic contact with the composite light extraction conductive layer 33. . The refractive index (η) of the first cladding layer, the first transparent conductive layer and the second transparent conductive layer are sequentially decreased, wherein the second transparent conductive layer is further covered with a transparent oxide layer to protect the light 17 201006003 II The polar body is not damaged by physical factors. Similarly, the refractive index of the transparent oxide layer is smaller than the refractive index of the second transparent conductive layer. With the above structure, the phenomenon of total reflection between the semiconductor layers can be reduced, and the amount of light consumed inside the light-emitting body can be reduced to increase the brightness of the light-emitting diode. The second transparent conductive layer has a low impedance characteristic, so that the current injected from the second electrode layer 36 is caused by the second transparent conductive layer to generate a uniform current spreading effect into the first transparent conductive layer. The light extraction structure 333 formed by the first transparent conductive layer forms an ohmic contact with the second cladding layer, so that the current flowing in the second transparent conductive layer flows into the luminescent epitaxial structure through the light extraction structure 333, so that the luminescent epitaxial structure is obtained. It produces a photoelectric effect and emits light. Then, the light emitted by the luminescent epitaxial structure can be effectively extracted by the light extraction structure 333, and is diffused to the outside by using the second transparent conductive layer having high transparency to improve the external luminous efficiency of the light emitting diode. The above is intended to be illustrative only and not limiting. Any changes or modifications to the spirit and scope of the present invention are intended to be included in the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a structure of a conventional light-emitting diode; FIG. 2A is a cross-sectional view showing a first embodiment of a light-emitting diode capable of improving light extraction rate; FIG. 2B A top view of a first embodiment of a light-emitting diode of the present invention for improving light extraction rate; and a c-sectional view of a second embodiment of the light-emitting diode of the present invention for improving light extraction rate; Μ 201006003 2D is a top view of a second embodiment of a light-emitting diode capable of improving light extraction rate of the present invention; FIG. 3 is a third embodiment of the light-emitting diode of the present invention capable of improving light extraction rate FIG. 3 is a plan view of a third embodiment of the light-emitting diode of the present invention capable of improving light extraction rate; FIG. 3C is a light-emitting diode of the present invention capable of improving light extraction rate剖面 A cross-sectional view of the fourth embodiment; and a 3D view is a plan view of a fourth embodiment of the light-emitting diode of the present invention which can improve the light extraction rate. [Main component symbol description] 11 : substrate; 12 · illuminating crystal structure; 13 : transparent window layer; 131 : concave hole; ϋ 14 : η type ohmic electrode; I5 : ρ type ohmic electrode; 21 : substrate; Insect crystal structure; 221: first slope coating; 222: luminescent layer; 223: second cladding layer; 23: composite light extraction conductive layer; 231: first transparent conductive layer; 19 201006003 232: second transparent conductive layer 233: light extraction structure; 24: buffer layer; 25: first electrode layer; 26: second electrode layer; 27: transparent oxide layer; 31: substrate; 3 2 · light-emitting crystal structure, 321 : first and second Layer 322: luminescent layer; 323: second cladding layer; 33: composite light extraction conductive layer; 331: first transparent conductive layer; 332: second transparent conductive layer; 333: light extraction structure; 34: buffer layer; 35: a first electrode layer; 36: a second electrode layer; and 37 · a transparent oxide layer.