JPH0410666A - Light-emitting element of gallium nitride-based compound semiconductor - Google Patents

Abstract

PURPOSE:To obtain light to be emitted in a white color by a method wherein zinc(Zn) and silicon(Si) are used as elements to be doped for an i-layer and the ratio of silicon to zinc is specified. CONSTITUTION:A gallium nitride-based compound semiconductor light-emitting element is provided with the following: an n-layer composed of an n-type gallium nitride-based compound semiconductor (AlxGa1-xN; including X=0); and an i-layer composed of an i-type gallium nitride-based compound semiconductor (AlxGa1-xN; including X=0). At the light-emitting element, elements to be doped for the i-layer are zinc(Zn) and silicon(Si), and the ratio of the doping density of silicon to the doping density of zinc is set at 1/100 to 1/200.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a gallium nitride compound semiconductor light emitting device that emits white light.

[Prior art]

Conventionally, blue light emitting diodes using GaN-based compound semiconductors are known. The GaN-based compound semiconductor is attracting attention because it has high luminous efficiency due to direct transition, and because it emits blue light, which is one of the three primary colors of light. A light emitting diode using such a GaN-based compound semiconductor is produced by growing an n-layer made of an n-type GaN-based compound semiconductor on a sapphire substrate directly or with a buffer layer made of aluminum nitride interposed therebetween. 1 on top of the layer
It has a structure in which an i-layer made of a type of GaN-based compound semiconductor is grown (Japanese Patent Application Laid-open No. 119196/1983,
(Japanese Unexamined Patent Publication No. 188977/1983).

Problem 1 to be Solved by the Invention However, zinc is used as a doping element for the i-layer in the light emitting diode having the above structure. For this reason, the emitted light color is fixed to blue, and other colors such as white cannot be emitted. Furthermore, there is no known light emitting diode that emits white light with a single chip. Therefore, in order to obtain white light emission, chips of blue, green, and red light emitting diodes were assembled into one lamp. Such lamps have a problem in that the manufacturing process is complicated. Therefore, an object of the present invention is to obtain white light emission with a single chip using a GaN-based compound semiconductor. [Means for Solving the Problems] The present invention provides an n-type gallium nitride compound semiconductor (Aj!
xGaI−xN: n layer consisting of (including X=O);
i-type gallium nitride compound semiconductor (AlXGa1-x
In a gallium nitride-based compound semiconductor light emitting device having one layer consisting of N;
l), and is characterized in that the ratio of silicon doping density to zinc doping density is 1/100 to 1/200.

[Operation and effects of the invention]

In the present invention, white light emission could be obtained by using zinc (Zn) and silicon (Si) as doping elements for the i-layer and setting the ratio of silicon to zinc to be 1/100 to 1/200.

【Example】

The present invention will be described below based on specific examples. First, a light emitting diode manufacturing apparatus according to this embodiment will be described. FIG. 2 is a sectional view of a vapor phase growth apparatus for manufacturing a gallium nitride light emitting diode of the present invention. The quartz tube 10 is sealed with an O-ring 15 at its left end and abuts the flange 14, and using a buffer material 38 and a fixture 39,
It is fixed to the flange 14 at several locations with bolts 46, 47 and nuts 48, 49, etc. The right end of the quartz tube 10 is sealed with an O-ring 40 and fixed to the flange 27 with screw fixing devices 41 and 42. An inner chamber 11 surrounded by a quartz tube 10 is provided with a liner tube 12 for guiding a reaction gas. One end 13 of the liner tube 12 is connected to a retaining plate 17 fixed to the flange 14.
The bottom portions 1 and 8 of the other end 16 are held on the quartz tube 10 by holding legs 19. As shown in FIG. 7, the planar shape of the liner tube 12 widens downstream, and the cross section of the liner tube 12 perpendicular to the long axis (X-axis) of the quartz tube 10 is shown in FIGS. 3 to 6. like,
It varies depending on the position in the X-axis direction. That is, the reaction gas is
It flows in the axial direction, but on the upstream side of the gas flow, it is circular as shown in Figure 2, and as it advances downstream (X-axis stop direction), it expands in the long axis direction with the Y-axis direction as the long axis. It has an elliptical shape that is reduced in the short axis direction, and at position A on the slightly upstream side where the susceptor 20 is placed, it has an elliptical shape in the vertical direction (
It has an oblate elliptical shape that is thinner in the X-axis direction and longer in the Y-axis direction. The length of the opening in the Y-axis direction in the sectional view taken along arrows IV--IV shown in FIG. 5 at position A is 7 cm, and the length in the X-axis direction is 1.degree. 2 cm. On the downstream side of the liner tube 12, a sample mounting chamber 21 having a rectangular cross section perpendicular to the X-axis in which the susceptor 20 is mounted is integrally connected. A susceptor 20 is placed on the bottom 22 of the sample placement chamber 21 . The susceptor 20 has a rectangular cross section perpendicular to the X-axis, but its upper surface 23 is gently inclined in the Z-axis stopping direction with respect to the X-axis. A sample, that is, a rectangular sapphire substrate 51 is placed on the upper surface 23 of the susceptor 20, and the gap between the sapphire substrate 51 and the upper tube wall 24 of the liner tube 12 facing it is 12 mm at the upstream portion and 12 mm at the downstream portion. Part 4mm
It is. An operating rod 26 is connected to the susceptor 20, and by removing the flange 27 and using the operating rod 26, the susceptor 20 on which the sapphire substrate 51 is mounted can be placed in the sample mounting chamber 21, or when crystal growth is finished. , the susceptor 20 can be taken out from the sample placement chamber 21. Furthermore, a first gas pipe 28 and a second gas pipe 29 are open on the upstream side of the liner pipe 12. The first gas pipe 28
It is located inside the gas pipe 29, and both pipes 28 and 29 are coaxial and have a double pipe structure. A large number of holes 30 are formed around the portion of the first gas pipe 28 that protrudes from the second gas pipe 29, and a large number of holes 30 are also formed in the second gas pipe 29. Then, the reaction gas introduced through the first gas pipe 28 is blown into the liner pipe 12, where it is first mixed with the gas introduced through the second gas pipe 29. The first gas pipe 28 is connected to the seventeenth second hold 31, and the second gas pipe 29 is connected to the second manifold 32. The first manifold 31 includes a carrier gas supply system I, a trimethyl gallium (hereinafter referred to as rTMGJ) supply system J, and a trimethyl aluminum (hereinafter referred to as rTMGJ) supply system
diethylzinc (hereinafter referred to as r) in the supply system of
DEZ) supply system and a silane (SiH2) supply system M are connected. The second manifold 32 is connected to an NH3 supply system H and a carrier gas supply system ■. A cooling pipe 33 for circulating cooling water is formed on the outer periphery of the quartz tube 10, and a high frequency coil 34 for applying a high frequency electric field is disposed on the outer periphery of the cooling pipe 33. Further, the liner pipe 12 is connected to the outer pipe 35 via the flange 14.
The carrier gas is introduced from the external pipe 35. Further, an introduction pipe 36 extends from the outside into the sample holding chamber 21 by passing through the flange 14 from the side.
A thermocouple 43 and its conductive wire 44 are installed to measure the temperature of the sample.
45, and is configured so that the sample temperature can be measured from the outside. With this device configuration, the mixed gas of TMG, TMA, H2, DEZ, and silane led through the first gas pipe 28 and the mixed gas of NH3 and H2 led through the second gas pipe 29 are mixed. The mixed reaction gases are mixed near the outlet of the tube and are led to the sample holding chamber 21 by the liner tube 12 and pass through the gap formed between the sapphire substrate 51 and the upper tube wall 24 of the liner tube 12. At this time, the flow of the reaction gas on the sapphire substrate 51 becomes uniform, and a high-quality crystal with little location dependence grows. When forming an n-type A II XG a, -XN thin film, the supply of DEZ and silane is stopped and the first gas pipe 2
8 and the second gas pipe 29. When forming an i-type A j2
It is sufficient if the respective mixed gases are allowed to flow out from the second gas pipe 29 and the second gas pipe 29. When forming an i-type A (l x Ga + - xN thin film, DEZ and silane are placed on the sapphire substrate 5.
The dopant element is doped into the growing A 12 XG a , -XN, and i
A I XG a , -XN is obtained. Next, a method for manufacturing the light emitting diode 50 having the configuration shown in FIG. 1 using this apparatus will be described. First, a single-crystal sapphire substrate 51 having an a-plane main surface that has been cleaned by organic cleaning and heat treatment is attached to the susceptor 20 . Next, the pressure in the reaction chamber 11 is set to lx 1O-5 Tor
After reducing the pressure to
The sapphire substrate 5 is heated at a temperature of 1100° C. while flowing into the liner tube 12 through the second gas pipe 29 and the external pipe 35.
1 was subjected to vapor phase etching. Next, the temperature was lowered to 400°C, H2 was bubbled through the first gas pipe 28 at 10β/min, and H2 was bubbled through TMA at 15°C at 50mA! /min, 1 H2 from the second gas pipe 29
1 min, and N Ha was supplied at 101/min for 2 min. In this growth step, a buffer layer 52 of AIN was formed to a thickness of approximately 500 nm. Next, when 2 minutes have elapsed, the supply of TMA is stopped, the temperature of the sapphire substrate 51 is maintained at 1150°C, and H2 is bubbled through the TMG at -15°C at 101/min from the first gas pipe 28. 200ml 1Z portion, lppm with H2
200 m11 of silane (SiH2) diluted to /min, H2 from the second gas pipe 29 at 101/min, NH3 at 10/min.
1/min for 15 minutes to form a high carrier concentration n layer 53 made of GaN with a film thickness of 2.5 JJm and a carrier concentration of 2×10 18 /cxd. Subsequently, the temperature of the sapphire substrate 51 is maintained at 1150° C., and H is similarly supplied from the first gas pipe 28 and the second gas pipe 29.
2 at 201/min, 10On+j of H2 bubbled in TMG at -15℃! /min, NH3 was supplied for 20 minutes at a rate of 101/min, the film thickness was 1.5cm, and the carrier concentration was 1X.
A low carrier concentration n-layer 54 made of GaN of 1016/cnl was formed. Next, the sapphire substrate 51 was heated to 900°C, and similarly,
H2 from the first gas pipe 28 and the second gas pipe 29, respectively.
1 oll for 1 minute, and 100 mjl of H2 bubbled in TMG at -15°C! 7 min, 2500 m Il of H bubbled in DEZ at 5°C 7 min, ippm with H2
Silane (Sift-) diluted to
From GaN to 50. One layer 55 was formed. At this time, the density of zinc in the first layer 55 is I x 1020/cn! The density of silicon was IX 10"/cr/! In this way, a multilayer structure as shown in FIG. 8 was obtained. Next, as shown in FIG. A SiO□ layer 61 was formed thereon by sputtering to a thickness of 2000 nm.Next, a photoresist 6 was formed on the 5 layer 02 layer 61.
2 was applied, and the photoresist 62 was formed by photolithography into a pattern in which the photoresist at the electrode formation site for the high carrier concentration n layer 53 was removed. Next, as shown in FIG. 10, the SiO□ layer 61 not covered by the photoresist 62 was removed using a hydrofluoric acid etching solution. Next, as shown in FIG.
, a low carrier concentration n layer 54 below it, and a high carrier concentration n layer 54
A part of the upper surface of the layer 53 was covered with CC6 under a vacuum degree of 0°04 Torr, a high frequency power of 0.44 W/cnt, and a flow rate of 10 cc/min.
After etching with 2F2 gas, dry etching was performed with Ar. Next, as shown in FIG. 12, the fifth layer 02 layer 61 remaining on the first layer 55 was removed with hydrofluoric acid. Next, as shown in FIG. 13, an AI layer 63 was formed over the entire surface of the sample by vapor deposition. Then, a photoresist 64 is coated on the AI layer 63, and the photoresist 64 is patterned into a predetermined shape using a photorin graph so that electrode portions for the high carrier concentration n layer 53 and the first layer 55 remain. did. Next, as shown in FIG. 13, using the photoresist 64 as a mask, the exposed portion of the lower AI layer 63 is etched with a nitric acid-based etching solution, the photoresist 64 is removed with acetone, and the high carrier concentration n-layer 53 is etched. Electrode 8.1 layer 55
The electrode 7 was formed. In this way, the old S (Metal-In) shown in FIG.
A gallium nitride-based light emitting device having a slater-3<em>1 conductor structure can be manufactured. When the light emitting intensity of the light emitting diode 10 manufactured in this way was measured, it was O.1 mcd. Further, the electroluminescence intensity of this single layer 55 was measured. The results are shown by curve A in FIG. It is understood that in addition to a peak at a wavelength of 480 nm (blue) appearing, the spectrum spreads toward longer wavelengths. That is, wavelength 550nm (green) 2 wavelengths 700nm (
(Red) also emits light, and as a result, the color visible to the human eye is white. Next, the first layer 55 was analyzed by SIMS. The results are shown in FIG. The distribution of zinc and silicon in layer 55 is understood. In addition, the density of silicon in one layer 55 is set to the density of zinc 1
xlQ2i1/cot, 1/100~1/2
Light emitting diodes were manufactured in the same manner by changing the ratio by 0.00. The electroluminescence intensity of the i layer 55 was measured and was similar to curve A in FIG. Further, the light emitted from the light emitting diode was white. In addition, the zinc density in one layer 55 is set to 5×1OI9/clT.
1~3X10”/cn! binding, for its zinc density,
Light emitting diodes were similarly manufactured by changing the silicon content at a rate of 1/100 to 1/200. The electroluminescence intensity of the first layer 55 was measured, and a curve almost similar to curve A in FIG. 14 was obtained. Furthermore, the light emitted by these light emitting diodes was white. In addition, the zinc density in one layer 55 is 2X1020/r++
A light emitting diode having a silicon density of 2 Xl0I6/cut was similarly manufactured using the method described above. and,
The electroluminescence intensity of one layer 55 of the light emitting diode was measured. The characteristics shown by curve B in FIG. 14 were obtained. That is, compared to curve A, the BL intensity at a wavelength of 480 nm (blue) decreases, and the BL intensity at a wavelength of 550 nm (green) decreases.
The EL intensity appears at the same level, and conversely, the EL intensity at a wavelength of 700 nm (red) is significantly larger. As a result,
The color visible to the human eye is red. Furthermore, the emission color of these light emitting diodes was red. In addition, the zinc density in one layer 55 is 5X10"/cnl ~
A plurality of light emitting diodes were manufactured in which the ratio of silicon density to zinc density was 1/200 to 1/1000, and the electroluminescence intensity of one layer 55 of the light emitting diodes was measured. The measurement result was a curve almost similar to curve B in Figure 14.Also, the color of those light emitting diodes as judged by humans was red.Also, for comparison, the zinc density was I x 10”/cd
A light-emitting diode without doping silicon was manufactured. Then, the electroluminescence intensity of one layer 55 of the light emitting diode was measured. The characteristics shown by curve C in FIG. 14 were obtained. That is, compared to curve A, wavelength 48
0 nm (blue) El, the intensity is much larger, wavelength 5
The EL intensity of 50 nm (green) appears at the same level, and conversely,
The EL intensity at wavelength 700r+n+ (red) is slightly small. The emitted light color of these light emitting diodes recognized by humans was blue. From the above, the following can be concluded. (1) When one layer 55 is doped only with zinc, the light emitting color of the light emitting diode is blue. (2) One layer 55 is doped with zinc and silicon, and the doping amount of silicon is 1/20 in proportion to the zinc density.
When the amount is relatively small in the range of 0 to 1/1000, the light emitted by the light emitting diode is red. (3) One layer 55 is doped with zinc and silicon, and the doping amount of silicon is 1/10 in proportion to the zinc density.
When the amount is relatively large (0 to 1/200), the light emitted by the light emitting diode is white. In the above example, silane was used as the silicon raw material, but tetraethylsilane ((C21(5) 4S+ :T
ES+) may also be used.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the structure of a light emitting diode according to a specific embodiment of the present invention, FIG. 2 is a block diagram showing an apparatus for manufacturing the light emitting diode, and FIGS. 3 to 6 are 7 is a plan view of the liner tube, FIGS. 8 to 13 are sectional views showing the manufacturing process of the light emitting diode, and FIG. 14 is a cross sectional view of the liner tube used in the device. FIG. 15 is a measurement diagram showing the results of electroluminescence measurement of the i-layer. FIG. 15 is a measurement diagram showing the results of SIMS analysis of the i-layer. 10°゛Light emitting diode 1-Sapphire substrate 2-Buffer layer 3-High carrier concentration n layer 4-Low carrier concentration n layer 5-I layer 7.8゛electrode

Claims (1)

[Claims] N-type gallium nitride compound semiconductor (Al_XGa_
1_-_XN; including X=0) and an i-type gallium nitride compound semiconductor (Al_XGa_1_-
In a gallium nitride-based compound semiconductor light emitting device having an i-layer consisting of Zn; The ratio to the doping density is 1/100 to 1/20
A light emitting element characterized in that: 0.0.