JPH0739247Y2 - Photocurrent distribution analyzer for light receiving element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an apparatus for analyzing a two-dimensional or three-dimensional photocurrent distribution in a light receiving element such as an amorphous silicon solar cell.

[Prior art]

When analyzing pinholes or other local deterioration in a photodetector such as amorphous silicon, or variations in film quality, in the past, a laser beam or pseudo-sunlight was condensed in a spot shape to form a two-dimensional surface of the photodetector. Scanning, measuring the output current from the light receiving element to obtain a two-dimensional characteristic distribution image, and evaluating and analyzing the uniformity of the light receiving element, the presence or absence of defects, etc. Page) is proposed.

[Problems to be solved by the invention]

However, in such an analyzing apparatus, since the spot-like light source is used for the scanning light, the output current is weak, the detection sensitivity is low, and the analysis accuracy is poor.

The present invention has been made in view of such circumstances, and an object thereof is to obtain a large photocurrent output, high sensitivity, and a photocurrent distribution analysis device for a light receiving element that is less affected by changes in a light source and noise. To provide.

[Means for solving problems]

In the present invention, linear light is used as scanning light instead of spot light.

The photocurrent distribution analyzer for a light receiving element according to the present invention includes a light source unit for projecting a linear light beam having a length that crosses the light receiving surface of the light receiving element that emits an electric signal when light is incident, and the light receiving unit for receiving the linear light beam. Two-dimensional characteristic distribution according to the image reproduction algorithm of CT method based on the means for relatively moving the light receiving element and the light source unit to scan the surface one-dimensionally from each direction and the one-dimensional photocurrent distribution obtained at each scanning. And an image forming section for obtaining an image.

[Action]

According to the present invention, a larger photocurrent output is obtained and sensitivity is higher than in the case where spot light is used, and it is possible to reduce the influence of changes in the light source and noise.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to the drawings showing an embodiment thereof. FIG. 1 is a perspective view of a photocurrent output distribution analysis device for a light receiving element according to the present invention (hereinafter referred to as a device of the present invention). In the figure, 1 is a machine frame, 2 is a sample stage, 3 is a light source, and 4 is a sample. Shows. The machine frame 1 is configured to integrally connect a base 1a and an upper board 1b arranged in parallel at a required distance with a connecting portion 1c to form a U-shape in a side view. A column 1d is erected on the upper surface of the base 1a, and a disc-shaped sample table 2 is rotatably and horizontally pivoted on the column 1d, and is rotated by a required angle around a center by a driving unit (not shown). The sample 4 is placed on this upper surface.

The sample 4 is, for example, an amorphous solar cell or the like, which is a light receiving element that generates a photoelectromotive force by projecting light, and is placed with its substantially central portion aligned with the rotation center of the sample table 1c. Reference numerals 4a and 4b are lead wires for extracting the photovoltaic power, which are connected to the sample 4, and are connected to an image forming unit 10 described later.

On the other hand, on the lower surface of the upper board 1b, the light source section 3 is reciprocally movable back and forth by being guided by a guide (not shown) between the connecting end of the upper board 1b with the connecting section 1c and the other end which is a free end. It is arranged.

FIG. 2 is a schematic cross-sectional view of the light source unit 3, in which a slit-shaped opening 3b is provided in the lower center of a hollow rectangular parallelepiped dark casing 3a, and a lens having a semicylindrical shape facing the opening ( Cylindrical lens) 3c is fixed, while a light source (such as a xenon lamp) 3d is arranged in the upper part of the dark casing 3a in a direction parallel to the opening 3b, and between the light source 3d and the lens 3c. The slits 3f are formed by arranging the one edges of the light shielding plates 3e, 3e so as to face each other with a dimension equal to the width dimension of the opening 3b, and the light from the light source 3d passes through the slit 3f and the opening 3b, and the lens 3
The light is condensed at c and projected as a linear light on the sample 4, and the light source unit 3 is moved, so that the sample 4 is moved as shown in FIG.
The scanning is performed as shown in FIG.

FIG. 3A is an explanatory view showing an example of scanning the light receiving element as the sample 4 with linear light, and shows the case where scanning is performed in two different directions A and B. The parallel lines in the drawing indicate the scanning positions at regular time intervals, and scanning is continuously performed in consideration of the response speed of the light receiving element as the sample 4.

Such scanning in the A direction gives outputs from the light receiving element as shown in FIG. 3B, and scanning in the B direction gives outputs from the light receiving element as shown in FIG. 3C. It is taken into the calculation unit 11 in the image construction unit 10 through 4a and 4b.

3 (b) and 3 (c) show the output from the light receiving element during each scanning, with the horizontal axis representing time and the vertical axis representing photocurrent.

Normally, the scanning of the light receiving element is performed about 180 times over the range of 180 ° by changing the direction around the light receiving element by 1 °.

The collected data is taken into the image forming unit 10 and synthesized as shown in FIG.
The image is constructed according to the algorithm of the Tomography method and displayed on the display unit 12.

As an example, the algebraic reconstruction method (ART method: Algebraic Reco
n struction Technique) will be outlined. Now, the solar cell having the photocurrent distribution f (x, y) is scanned and its data P (X, θ), where 0 ≦ θπ, θ = θ ₁ , θ ₂
... is that we have obtained a θ _m). Assuming that this is displayed on the image display unit, its initial value is f ⁰ (x, y), its data in the θ ₁ direction is first obtained by calculation, and this is set as R ⁰ (X, θ ₁ ). R ⁰ (X, θ ₁ ) is compared with the actual scanning data P (X, θ ₁ ) in the θ ₁ direction, and the difference is corrected so as to be smaller. This operation is also performed from the θ ₂ , θ ₃ ... θ _m direction, and the obtained value of each pixel is set as the first recent value f ¹ (x, y). Further, by the same operation, f ¹ (x, y) is changed to temporary data R
¹ (X, θ) is calculated, and this is the true scanning data P (x, θ)
The second recent value f ² (x, y) is calculated so as to be close to. After that, the same operation is repeated until the difference between R ¹ (X, θ) and P (X, θ) becomes sufficiently small, and the pixel value f ¹ (x,
Let y) be the reconstruction result.

Thereafter f ⁱ (x, y) from the ^{f i + 1 (x, y} ) is ... the Yuku seeking This is done by such additive ART method represented by the following formula, for example.

However, C (X, θ) is the number of pixels. FIG. 4 is an explanatory view showing another configuration of the light source unit 3 of the present invention, in which the light from the laser beam generator 3h is reflected by the reflecting mirror 3i to be the sample 4. While mutually positioning so as to project on the light receiving element, the reflecting mirror 3i is repeatedly moved around the axis 3j within the range of the required angle θ to linearly form the laser beam on the light receiving element while receiving light from the light source section 3 or the light receiving section. The element is moved to scan the entire light receiving element.

The other structure is substantially the same as the structure shown in FIGS.

With such a configuration, it is possible to perform scanning using the linear light similar to that of the embodiment shown in FIGS. 1 to 3, and there is an advantage that the configuration is simplified.

FIG. 5 is a schematic cross-sectional view of a light source section showing another embodiment of the present invention, in which a filter is provided in the dark casing 3a between the cylindrical lens 3c and the light shielding plates 3e, 3e, facing the slit 3f. 3g is detachably installed.

As the filter 3g, a plurality of filters having different transmission wavelengths are prepared in advance, and the light receiving surface of the light receiving element serving as the sample 4 is scanned with light having different wavelengths. As a result, the linear light reaches different wavelengths at different depths from the light receiving surface of the light receiving element, and as a result, one-dimensional photocurrent distribution data is obtained for different depth portions.

Therefore, this data is processed by the algorithm of the CT method similarly to the embodiment shown in FIGS. 1 to 3 to obtain a two-dimensional photocurrent distribution image for each depth.

Since such a two-dimensional photocurrent distribution is obtained for each portion having a different depth from the light receiving surface of the light receiving element, a two-dimensional photocurrent distribution image is finally obtained for each portion in the thickness direction of the light receiving element, and the three-dimensional photocurrent distribution is obtained. It is possible to know the original photocurrent distribution.

〔effect〕

As described above, in the present invention, the scanning of the light-receiving surface of the light-receiving element is replaced with the conventional spot light, and linear light having a length that traverses the light-receiving surface is used. The present invention has excellent effects such as an increase in detection sensitivity and an increase in detection accuracy, and a more accurate two-dimensional or three-dimensional analysis of photocurrent distribution.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a schematic enlarged sectional view of a light source section, and FIG. 3 is a scanning example for a light receiving element and an explanation of respective one-dimensional photocurrents. 4 and 5 are principle views showing another example of the light source section, and FIG. 5 is a schematic sectional view showing another example of the present invention. 1 ... Machine frame, 2 ... Sample stand, 3 ... Light source part, 3a ... Dark casing, 3b ... Opening part, 3c ... Lens, 3d ... Light source, 3e ...
Light-shielding plate, 3f ... Slit, 3g ... Filter, 4 ... Light receiving element, 10 ... Image reconstruction unit, 11 ... Calculation unit, 12 ... Display unit

Claims (2)

[Scope of utility model registration request] 1. A light source unit for projecting linear light having a length that traverses a light receiving surface of a light receiving element that emits an electric signal when light is incident thereon,
Based on the one-dimensional photocurrent distribution obtained during each scanning, and means for relatively moving the light-receiving element and the light source section so that the light-receiving surface is one-dimensionally scanned from a plurality of directions with this linear light, the CT method An image forming unit for obtaining a two-dimensional characteristic distribution image according to an image reproduction algorithm, and a photocurrent distribution analyzing apparatus for a light receiving element. 2. A photocurrent distribution analyzing apparatus according to claim 1, wherein the scanning linear light beams having different wavelengths are used.