JPH0738138A - Ultraviolet sensor - Google Patents

Abstract

PURPOSE:To enable an ultraviolet sensor to be lessened in sensitivity to unnecessary ray which is of certain wavelengths and absorbed in an Si substrate, enhanced in sensitivity to ultraviolet ray, and lessened in sensitivity to visible ray to infrared ray by a method wherein a conductive film is provided between an amorphous semiconductor junction diode and a semiconductor substrate. CONSTITUTION:An ITO film 2 is formed on a single crystal Si substrate 1 as a transparent conductive film, and an N-type a-SiC: H film 3, an intrinsic a-SiC: H film 4, and a P-type a-SiC: H film 5 are successively formed for the formation of an amorphous semiconductor diode. Then, an ITO film 6 is formed as a transparent conductive film. The ITO film 2 is large in optical gap and transmissive to visible to infrared ray transmitted through an amorphous semiconductor layer to produce photocarriers inside the semiconductor substrate 1. The ITO film 2 serves to prevent photocarriers from being reflected to an amorphous semiconductor junction so as not to make photocarriers detected as a photocurrent. By this setup, an ultraviolet sensor of this constitution can be enhanced in optical sensitivity to ultraviolet ray.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet light sensor,
Particularly, it relates to an ultraviolet light sensor having high sensitivity in the ultraviolet region and low sensitivity in the infrared region.

[0002]

2. Description of the Related Art Conventionally, as an ultraviolet light sensor of this type, S
Prototypes of a pn junction diode using i, a Schottky diode using GaAs, etc. have been manufactured. Especially Ga
The Schottky diode using AsP has received the most attention because of its excellent stability under irradiation with ultraviolet light and the low dark current. However, there are problems that the cost is high and the sensitivity to ultraviolet light is low. In order to solve this, a p-i-n junction diode using amorphous Si or amorphous SiC, which has a high absorption coefficient in the ultraviolet region and can be formed at low cost, has been studied.

[0003]

However, when the p-i-n junction diode is formed directly on a single crystal Si substrate, photocarriers excited by light in the visible to infrared region penetrating into the substrate are exposed to the light. There was a serious problem of reaching the pin junction diode and increasing the sensitivity in unnecessary wavelength regions other than the ultraviolet region. As a measure against this problem, it is conceivable to provide an optical filter on the incident light side of the diode, but this causes a large increase in manufacturing cost, and an inexpensive ultraviolet light sensor could not be realized.

The present invention solves the above-mentioned conventional problems, and
It was made to reduce the sensitivity in the unnecessary wavelength range due to the absorption of light by the i substrate, and to provide an ultraviolet light sensor with high sensitivity in the ultraviolet range and low sensitivity in the visible to infrared range at low cost. With the goal.

[0005]

The ultraviolet light sensor of claim 1 is characterized in that a conductive film is provided between the amorphous semiconductor junction diode and the semiconductor substrate.

The ultraviolet light sensor of claim 2 is characterized in that the conductive film of claim 1 is a transparent conductive film.

The ultraviolet light sensor of claim 3 is characterized in that the conductive film of claim 1 is a metal material.

[0008]

The transparent conductive film provided between the amorphous semiconductor junction diode and the semiconductor substrate has a large optical gap and transmits light in the visible to infrared region that has passed through the amorphous semiconductor layer.
The photocarrier generated in the semiconductor substrate by the transmitted light cannot reach the amorphous semiconductor junction due to the presence of the transparent conductive film, and acts so as not to be detected as a photocurrent.

The metal film provided between the amorphous semiconductor junction diode and the semiconductor substrate reflects and absorbs light in the visible to infrared region that has passed through the amorphous semiconductor layer and penetrates the light into the semiconductor substrate. It acts to prevent it.

[0010]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic sectional view showing an embodiment of the ultraviolet light sensor of the present invention. Example 1 In FIG. 1, 1 is a single crystal Si substrate (semiconductor substrate), 2
Is an ITO film (transparent conductive film), 3 is an n-type a-SiC: H film (n-type amorphous semiconductor film), 4 is an intrinsic a-SiC: H film (amorphous intrinsic semiconductor film), 5 is p Type a-SiC: H film (p-type amorphous semiconductor film), 6 is an ITO film (transparent conductive film)
Indicates.

A single crystal Si substrate 1 is used as a substrate, and ITO is formed as a transparent conductive film on the substrate 1 by a sputtering method.
Film 2 was deposited to a thickness of 50 nm. Then plasma CV
The n-type a-SiC: H film 3 having a thickness of 20 nm and an intrinsic a
-SiC: H film 4 of 50 nm, p-type a-SiC: H film 5
Was deposited to a thickness of 5 nm. Finally I as a transparent conductive film
The TO film 6 was deposited to 50 nm. This is designated as Sample A.

For comparison, a sample B having no ITO film 2 was prepared and the spectral sensitivities of the two samples were compared. As a result, 200 nm
No significant change was observed in both photosensitivities in the wavelength region of ˜400 nm, and in the wavelength region of 500 nm to 800 nm, the photosensitivity of sample A decreased to 50% or less of that of sample B. The photosensitivity of the samples A and B in the wavelength range of 200 nm to 400 nm is 150 to 2 as compared with that of the conventional Schottky diode made of GaAsP.
Increased by 00%. Embodiment 2 FIG. 2 is a schematic sectional view showing another embodiment of the ultraviolet light sensor of the present invention. In FIG. 2, 1 is a single crystal Si substrate (semiconductor substrate), 7 is a Cr film (metal film), 3 is n-type a-Si.
C: H film (n-type amorphous semiconductor film), 4 is intrinsic a-Si
C: H film (amorphous intrinsic semiconductor film), 5 is p-type a-Si
C: H film (p-type amorphous semiconductor film), 6 represents an ITO film (transparent conductive film).

A single crystal Si substrate 1 was used as a substrate, and a Cr film 7 having a thickness of 50 nm was deposited as a conductive film on the substrate 1 by a sputtering method. Then, the n-type a-SiC: H film 3 is formed to a thickness of 20 nm by using a plasma CVD method,
C: H film 4 is 50 nm, p-type a-SiC: H film 5 is 5 n
m was formed into a film. Finally, an ITO film 6 was deposited to a thickness of 50 nm as a transparent conductive film. This is designated as Sample C.

For comparison, a sample D having no Cr film 7 was prepared and their spectral sensitivities were compared. As a result, 200 nm
No significant change was observed in both photosensitivities in the wavelength range of ˜400 nm, and in the wavelength range of 500 nm to 800 nm, the photosensitivity of sample C decreased to 50% or less of that of sample D. The photosensitivity of the samples C and D in the wavelength range of 200 nm to 400 nm is 150 to 2 as compared with that of the conventional Schottky diode made of GaAsP.
Increased by 00%.

[0015]

According to the present invention, an ultraviolet light sensor having high photosensitivity in the ultraviolet region can be realized. Further, according to the present invention,
It is possible to realize an ultraviolet light sensor that suppresses light sensitivity in the visible to infrared region without using an expensive optical filter.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of an ultraviolet light sensor of the present invention.

FIG. 2 is a schematic cross-sectional view showing another embodiment of the ultraviolet light sensor of the present invention.

[Explanation of symbols]

 1 Single Crystal Si Substrate 2 ITO Film 3 n-type a-SiC: H Film 4 Intrinsic a-SiC: H Film 5 p-type a-SiC: H Film 6 ITO Film 7 Cr Film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuhei Tanaka 3-5-11 Doshomachi, Chuo-ku, Osaka City, Osaka Prefecture Nippon Sheet Glass Co., Ltd. Hamamatsu Photonics Co., Ltd.

Claims (3)

[Claims] 1. An ultraviolet light sensor, comprising a conductive film provided between an amorphous semiconductor junction diode and a semiconductor substrate. 2. The ultraviolet light sensor according to claim 1, wherein the conductive film is a transparent conductive film. 3. An ultraviolet light sensor, wherein the conductive film according to claim 1 is a metal material.