JPS61216490A - Semiconductor light position detector - Google Patents

Abstract

PURPOSE:To improve the position detecting accuracy by setting to allow the length of current collecting electrodes, specific resistance, width and thickness of a material to satisfy specific conditions. CONSTITUTION:The length of current collecting electrodes is represented by #l, the specific resistance of a material is rhom, the width is w and the thickness is d, and P is represented by l.rhom/w.d. The rhos/P (where rhos is the sheet resistance of a resistance layer) in the relationship between the position detecting accuracy and rhos/P is confirmed to have k 167 according to experiments to have the value to indicate substantially constant value K for the position detecting accuracy, and d, w, l and rhom are so selected that rhos/P becomes the value K or larger to improve the position detecting accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a semiconductor optical position detector using amorphous silicon as a material for a semiconductor layer.

(Prior Art) The present applicant previously proposed a semiconductor optical position detector according to Japanese Patent Application No. 161470 of 1982.

This semiconductor optical position detector includes a semiconductor layer formed by forming a 9-type amorphous silicon layer on one surface of an i-type amorphous silicon layer and an n-type amorphous silicon layer on the other surface. When a resistive layer is formed on both sides, the voltage is 4K.

It has a configuration in which a current collecting electrode is disposed on the resistance layer.

(Problems to be Solved by the Invention) By the way, in a well-known position detector using single crystal silicon, the semiconductor layer itself functions as a resistance layer.
The sheet resistance of the resistive layer is significantly higher than the resistance of the current collecting electrode (for example, 1 knlo,'), so that the resistance of the current collecting electrode does not significantly affect the detection accuracy.

On the other hand, in the conventional position detector using amorphous silicon, the resistance layer is formed of ITO or the like, so its sheet resistance is extremely low (for example, 50Ω/
mouth). To this end, the light beam is moved to position t?, as shown in FIG. When the current is incident on the resistor layer 4, a potential distribution occurs in the current collecting electrode 5as5b when the photogenerated current flows through the resistance layer 4, which causes a problem in that the accuracy of position detection is reduced. In addition,
In the figure, lead wires 7 for extracting current are connected to current collecting electrodes 5m and 5bK, respectively.

(Means for Solving the Problems) In order to solve such conventional problems, in the present invention, an L-type amorphous silicon layer is formed on one surface of the L-type amorphous silicon layer, and an n-type amorphous silicon layer is formed on the other surface. The device includes a semiconductor layer formed by forming a silicon layer, a resistive layer having light-transmitting properties is formed at least on the light-receiving surface side of the semiconductor layer, and a current collecting electrode for extracting position signals is arranged at the end of the resistive layer. The position detection accuracy and
i ρ, / (where ρ6 is the sheet resistance of the above resistance layer) ρ, /l! in relation to d ! The length t of the txi, the material's specific resistance ρ
I'm trying to set it up.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1(3) is a plan view showing an embodiment of the semiconductor optical position detector according to the present invention, lines A-A' and B-8' in FIG. FIG. FIG. 2 is a partially sectional perspective view of this embodiment.

In the semiconductor optical position detector according to this embodiment, a resistance layer 2 made of a light-transmitting conductive film is formed on a substrate 1 made of glass or the like by a starch drop method or a vacuum evaporation method. A semiconductor layer 3 is formed on the upper surface of this resistive layer 2, and a resistive layer 4 made of the same material as the resistive layer 2 is further formed on the upper surface of this layer 3 by the same method. Note that the film thickness of the resistance layers 2 and 4 is set to, for example, about 10,001 mm.

The semiconductor layer 3 is made of p-type amorphous silicon 431, 1ffi amorphous silicon layer 32 as shown in FIG.
It has a three-layer structure consisting of seven layers 33 of n-type amorphous silicon and seven layers 33 of n-type amorphous silicon. Note that these layers were formed by CVD (ebI
! nical vapor dspomltion)
The film thicknesses dptdi b and dn are 9, for example, d, -200X to 250X, di=4
000~6000X and dn=300~500XVc
Set.

A pair of bar-shaped X-direction current collecting electrodes 5m and 5b are disposed opposite to each other at both ends of the resistance layer 20, and similarly, the resistance layer 40
A pair of y-direction current collecting potentials 6a*6b are arranged opposite to each other at both ends. And these current collecting electrodes 5 a e 5
A ninth lead wire 7 from which current is taken out is connected to the center of b a 6 a t 6 b.

Now, as shown in Fig. 4, electrodes 5m, 5b and 6m
e 6 The thickness of b is a, @ is W, the length is ρ, and the specific resistance of the material is ρ. The sheet resistance of the resistive layer 2.4 is ρ.
, the detection accuracy exhibits a nearly constant value when the sheet resistance and current collection are at their peak (Okentaka 167) or higher.

Therefore, d so that bar〇〇 is greater than or equal to the above value
, v, t and ρ. By selecting , it is possible to improve the detection nc, and experiments have confirmed that the detection nc is about 167.

Therefore, in this embodiment, the sheet resistance of the resistance layer 2.4 is 50
Aluminum (ρ exhaust 2
．． 65
= 10000 (X), w = 0.8 (cd,
Set L = 8-, so that the distance to ρ” is approximately 189
(>167).

The operation of this embodiment will be explained below.

Now, as shown in Fig. 6 ca+, (bl, (e)), when a light beam enters the semiconductor optical position detector,
A photogenerated current is generated at the incident position P. At this time, in the resistance layer 2, the resistance r between the incident position P and the electrode 51.5b
The above IIIL flow is divided by process 1+rx2, and in resistance layer 4, the resistance r between position P and 116m and 6b is
Since the above current is divided by a1 e ry2.

From II lotus 5 m, 5 b, the current IK1*'x2 is also t('16 m.

Current air 1 and 1y2 are each taken out from 6b.

Each of the above divided currents x 1. 'x2+Ty1. Iy2 is normally input to a signal processing circuit as illustrated in FIG.

This processing circuit includes a preamplifier 13 to which each of the above-mentioned currents is input.
~16 and the current sum Ix1+■x21? and ry1+r,
2 t-get adders 17 and 18 and ``IIL current difference I
Obtain subtractors 19 and 20 to obtain G1-r G2 and I, l-AIR 2, and obtain the ratio of each output of adder 17 and subtractor 19 and the ratio of each output of adder 18 and subtractor 20. Divider 2
The light incident position signal PX in the X direction shown in equation (1) below and the light incident position signal P in the y direction shown in equation (2) below are obtained from dividers 21 and 22, respectively. Output.

Note that, according to this processing circuit, it is possible to obtain a position signal that is not affected by the intensity of incident light and its changes.

The output characteristics of the position detector according to this embodiment are as shown in the graph of FIG. In this graph, each hot spot on the solid line indicates a detection position with respect to the intersection of the dotted lines where the light beam is incident. In the case of this example, it can be seen from the figure that the detection error t/L ((6) is 0.8% at maximum.

On the other hand, under the same conditions only d is d = 3000K
If the value of ρ is set to approximately 57 (<167), the output characteristics will be as shown in Figure 9. In this case,
The detection error is 1.5 inches, which means that the detection accuracy is worse than in the case of this embodiment. Note that each figure shows the detection error only in the X direction.

By the way, in the above embodiment, the substrate 1 is made of glass, and the resistive layer 2 is made of a transparent conductive film. Therefore, according to this embodiment, even if the light beam is incident on the substrate l side, the light beam incident position can be detected. In other words, the position detector according to this embodiment can detect the incident position of the light beam no matter which surface of the semiconductor layer 3 the light beam is incident on.

In addition, when the resistance layer 4 side is limited to the light-receiving side, both the resistance layer 2 and the substrate 1 may be formed of a light-shielding material. Further, when the substrate l side is limited to the light receiving side, the resistive layer 4 may be formed of a light-shielding material.

In the above embodiment, as shown in FIG. 1, a pair of t-poles 5m, 5b and 6a, 6b are provided in each of the resistance layers 2 and 4, but each voltage is changed as shown in FIG. It is also possible to arrange them all in the resistance layer 4. However, in this case, instead of the resistive layer 2, a common electrode 23 made of a conductive film is provided.

Further, in the above embodiment, there is a resistive layer 2 on the nl- side of the semiconductor i3.
is formed, and the resistance layer 4 is formed on the second layer side, but p+r
One layer may also be formed in the opposite manner.

(Effects of the Invention) As explained above, ρ in the first semiconductor according to the present invention
, 4- has a value within the region where the position detection accuracy is a nearly constant value d: (, the length of the current collection image 6,
Since the specific resistance ρffl, width W, and thickness d of the material are set, the position detection accuracy can be improved.

[Brief explanation of the drawing]

FIG. 1 shows an actual example of the semiconductor optical position detector according to the present invention, and FIG. Figure, Figure (c) is Figure (
), FIG. 2 is a perspective view of the implementation row shown in FIG. 1, FIG. 3 is a partially enlarged view showing the structure of the semiconductor layer, and FIG. 4 is a current collecting image. FIG. 5 is a graph showing how the detection error changes with respect to the resistance of the resistance layer and the resistance of the current collecting pole. FIG. 6 is the effect of the embodiment shown in FIG. FIG. 7 is a clock diagram showing an example of the processing circuit, and FIG. 8 shows the output characteristics when (ρa/-!5>d is approximately 1891CI) in the embodiment shown in FIG. Figure 9 shows the ratio of the resistance of the resistance layer to the resistance of the current collecting electrode (ρν2
A graph showing the output characteristics of the position detector when fc is set to about 57. Figure 10 shows the state of potential distribution in the current collection image J3A
FIG. 11 is a perspective view schematically showing another embodiment of the semiconductor optical position detector according to the present invention. DESCRIPTION OF SYMBOLS 1...Substrate, 2, 4...Resistance layer, 3...Semiconductor layer, 5m, 5b, 6 head, 6b... Collection 1
[Electronic couple E, 7... Reit 9 wire. Figure 2 A Figure 3 Figure 4 Figure 5 Figure 6] 2 Figure 7 Figure 8 d = 10000 (in) Figure 9 d -3000 (A) Figure 10

Claims (1)

[Claims] A semiconductor layer is formed by forming a p-type amorphous silicon layer on one surface of an i-type amorphous silicon layer and an n-type amorphous silicon layer on the other surface, and a light-transmitting layer is provided at least on the light-receiving surface side of this semiconductor layer. In a semiconductor optical position detector, in which a resistive layer with a characteristic of , ρ_s is ρ_s/(lpm
The length l, the specific resistance ρ_m of the material, the width w, and the thickness d of the current collecting electrode are set so that /wd) has a value within a region in which the position detection accuracy is approximately constant. A semiconductor optical position detector characterized by the following.