JPS6314482A - Thin-film semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a color sensor capable of discriminating colors correctly, by piling up three or more PIN or PN junction layers on a substrate and forming electrodes on the top and the bottom of each layer such that both the electrodes have light transmission properties or such that one of them has light transmission properties while the other has non-transmitting properties. CONSTITUTION:Incident light 1 first passes through a first layer consisting of a P-type semiconductor 4a, an I-type semiconductor 5a and an N-type semiconductor 6a, where short-wavelength components of the incident light 1 are absorbed by the PIN junction of the first layer. The residual light which has not been absorbed by the first layer passes through a second layer consisting of a P-type semiconductor 4b, an I-type semiconductor 5b and an N-type semiconductor 6b, where intermediatewavelength components of the incident light 1 are absorbed by the PIN junction of the second layer. Further, the residual light which has not been absorbed either by the second layer passes through a third layer consisting of a P-type semiconductor 4c, an I-type semiconductor 5c and an N-type semiconductor 6c, where long-wavelength components of the incident light 1 are absorbed by the PIN junction of the third layer. The light components absorbed by the respective layers are converted photoelectrically by the PIN junctions and taken out as photocurrent. Since the upper layer serves as a color filter of the lower layers, there is no need of providing an external color filter.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a single-film semiconductor device used as a color sensor for determining the color of light.

<Prior art> In recent years, there has been a demand for color sensors that are used for sorting items by color code, identifying the colors of threads, wool, pigments, and dyes, reading the colors of designs, adjusting color cameras, etc. Color sensors have been developed.

The structure of a conventional color sensor is shown in Figure 3. This color sensor was jointly developed by the Nagoya Heavy Industries Research Institute and the Faculty of Engineering, Nagoya University (Kato, H., Morinaga, 1993).

S., Yoshida, M., and Ar1zu.
n+i, T, , ”ANew I nLegra
ted Transducer for Co1
Our Distinction,' Journal
of Physics E:5cient
ific In5tru+aenLs, vol.
9. pp, 1070 (072, Dec, 1976
, Kato, Matsuda "Semiconductor Color Discrimination Element", 1981 IEICE Satoshi National Conference Lecture Paper! 1,53-5,11
p, 2-336-2-337. April 1981, Kato.

Matsuda, Ueda "Color identification element for industrial robots".

r Automation Technology J, Volume 12, No. 6, pp, 11-1
4.Refer to June 1980, etc.), and 4 to 8 [Ω・c
On an n-type silicon (Si) substrate 18 having a conductivity of 11I], 5nC1,
・Spray xH2O-HCI-HzO mixture to form Sn 0216, and add acid 1 arsenic (SiO
2) Separate into three photodiodes with Su+02-3i junction, stack red, blue, and green filters 12, 13, and 14 on top of each other, and then In addition to coating with an infrared cut filter, gold 315 is extracted from each photodiode, and Si
An ohmic contact electrode 19 is drawn out from the temporary 18, and the light that has passed through red, blue, and green filters is received by independent photodiodes, and the color is determined by the combination of each output.

In addition, Sanyo Electric Co., Ltd. has amorphous optical sensors and red,
We are commercializing an amorphous color sensor that uses color filters such as blue and green.

However, in order to accurately discriminate colors with this type of color sensor, it is necessary to make sure that the three photodiodes are uniformly illuminated, and if the sensor position or the angle of the light-receiving surface changes, color discrimination becomes difficult. It has the disadvantage that errors occur. Furthermore, since three color filters are required, there is also the problem that the performance of the color sensor is largely influenced by the performance of the color filters.

Therefore, the applicant previously announced a color sensor with pnpf23fi that does not require a color filter, as shown in FIGS. ``Television Society Technical Report''.

E D418. December 1978, precious wood "Semiconductor color sensor and its applications", ? Newly developed solid-state sensor and its application technology, Seminar Text J, pp, 57
-6J December 1980, Kayoshi, Yamane, Meiki "Applications of semiconductor color sensors, li' 1st "Basics and Applications of Sensors" Symposium Proceedings J, B5-1.91),
47-48, June 1981, etc.), this color sensor is a Si semiconductor with a p region 22, as shown in FIG. 4(a).
．． A simple pnptW structure consisting of 24 and n region 23 is formed, and TLi 25, 26, 27 are drawn out from each region, and as shown in FIG. 4(b), two photodiodes It is represented by an equivalent circuit in which PD and PD are connected in series in opposite directions, and the photodiode P
Utilizing the difference in the spectral 5 degree characteristics of photodiode PD2 and photodiode D, photodiode PD2 with a shallow pn'bF junction perceives short wavelength light, and photodiode PD2 with a deep pn junction perceives long wavelength light. I am beginning to feel that
Si itself serves as a filter. Therefore, no color filter is required, and reference numeral 21 is an infrared Keisen cut/fill.

<Problems to be solved by the invention> However, the color sensor shown in FIGS. 4(a) and 4(b) above has the following problems:
Because it uses two-color separation, wavelengths can be read, but color discrimination may differ from human vision. For example, even if red and blue are mixed to make purple, this color sensor cannot distinguish between yellow and green. It has been difficult to accurately distinguish between colors.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a color sensor that can accurately discriminate colors.

Means for Solving the Problems In order to achieve the above object, the one-film semiconductor device of the present invention has three or more layers of pin junctions or p1 junctions stacked on a substrate,
Above and below each layer, electrodes are formed that are transparent to light or one of which is opaque.

Effect> The wavelength dependence of the intensity of light guided to each bonding layer is determined by measuring the photocurrent detected from the electrodes at both ends of each bonding layer.

<Example> Hereinafter, the present invention will be described in detail based on an illustrated example.

1 and 2 show an embodiment of the thin film semiconductor device of the present invention. FIG. 1 is a simplified cross-sectional diagram showing the structure, and FIG. 2 shows the wavelength of the spectral sensitivity of each layer. It is a characteristic diagram showing dependence.

As shown in FIG.
inductive Oxide; TC○) 3a, 1st
layer p-type semiconductor (p region) 4a, first layer i-type semiconductor (
i region) 5a, first layer n-type semiconductor (n region) 6a-T
CO3b, second layer p-type semiconductor 4b, second FJ n-type semiconductor 5b, second layer n-type semiconductor 6b, TCO3c, third layer p-type semiconductor 4c, third layer i-type semiconductor 5c, third layer
An n-type semiconductor 6c of N and an ohmic contact electrode 7 are successively formed.

With the above configuration, the incident light 1 first passes through the glass substrate 2 and the TCO 3a, and is partially absorbed by the pin junction of the first layer consisting of the type semiconductor 4a, the n-type semiconductor 5a, and the n-type semiconductor 6a. be done. The light absorbed here is the incident light 1
The 0-order short wavelength component of the light, which is not absorbed by the pin junction of the first layer, passes through the TC○3b and passes through the TC○3b, which is the short wavelength component of the Part of the pin junction between the two layers is formed. The light absorbed here is the middle wavelength component of the incident light 1. Furthermore, the second.
The light that is not absorbed even at the pin junction of II is TCO3
The p-type semiconductor 4e, the n-type semiconductor 5C and n
It is absorbed by the pin junction of the third layer made of type semiconductor 6C. The light absorbed here is the long wavelength component of the incident light 1. Then, the light absorbed in each layer is photoelectrically converted by the pin junction and becomes a photocurrent, and the TCO3a, 3b, 3c
and currents ia and ib from the ohmic contact electrode 7
, ic. In addition, the symbols 8a, 8b,
Sc is an ammeter for measuring the output currents ia, ib, and ie of each layer, respectively. Here, in the above configuration, since the upper layer serves as a color filter for the lower layer, the external color filter is air.

2I2I shows the wavelength dependence of the light current ia, ib, and ie in each layer of the thin film semiconductor device shown in FIG. corresponds to green light, and photocurrent IC corresponds to red light. Therefore, these photocurrents ia, ib, i
By comparing and examining the magnitude of c, the color of the incident light 1 can be determined.

In this example, the semiconductor is amorphous (a+
aorpbous; amorphous) silicon (Si)
Although a semiconductor was used, the optical energy gap (optical
semiconductors with different energy gaps, such as amorphous silicon nitrogen (α-3iN), amorphous silicon carbon (α-3iC), amorphous silicon germanium (α-5iGe), n-IV group hexagonal semiconductors,
Polycrystalline silicon or the like may be used, and the TCO may be of any material as long as it has light transmittance, and so-called transparent electrodes such as gold (Au), platinum (Pt), 1! (Ag), aluminum (AI) and other metal 3 films (thickness 50 [included] ungrooved)
Furthermore, in this example, the film thickness of each part is 50 to 200 [people] for the p-type semiconductor and the n-type semiconductor, and 50 to 200 [people] for the i-type semiconductor. The input value is 500 to 10,0 OOr, and the TCO is 600 to 700 people.
It is not limited to an n-junction, and any suitable one such as a nip junction, an np junction, or a pn junction may be selected. Note that the order of the junctions does not need to be the same within the thin film semiconductor device;
When the liGl semiconductor device is fabricated on a substrate having optical transparency, incident light is introduced from the substrate side,
If it is formed on a light-opaque substrate, the incident light may be introduced from the side opposite to the substrate, but in this case, the ohmic contact electrode 7 on the side opposite to the substrate,
It is necessary to use a transparent electrode with light transmittance.

<Effects of the invention> As described above, with the structure of the present invention,
To realize a high-performance color sensor that does not require color filters, so that color discrimination performance is not affected by color filters, and that can discriminate colors from each other over a wide range using one continuous joint structure. By unifying the light-receiving surface, it is possible to reduce variations and errors caused by the angle of incident light and the positional relationship of the sensor, simplifying the manufacturing process, reducing costs, and making the product more compact. can be expected to significantly improve color discrimination accuracy.

[Brief explanation of the drawing]

FIG. 1 is a simplified cross-sectional schematic diagram showing the structure of an embodiment of the thin film semiconductor device of the present invention; FIG. 2 is a spectral fear characteristic diagram showing the wavelength dependence of photocurrent detected by each layer; Figures 3 and 4 (a)
(b) shows an example of a conventional color sensor, and FIG.
Figures 4(a) and 4(b), which are simplified cross-sectional schematic diagrams showing the structure of a three-color separation type one-chip color sensor using color filters, are two-color separation type color sensors with a simple PNP structure; Figure (a
) is a simplified cross-sectional schematic diagram showing the structure, and FIG. 4 (b>) is its equivalent circuit diagram.

Claims (1)

[Claims] (1) A thin film semiconductor device characterized by laminating three or more layers of pin junctions or pn junctions on a substrate, and forming electrodes on the top and bottom of each layer, one of which is transparent or one of which is opaque. .