JPS62176173A - Manufacture of photoelectric conversion device - Google Patents

Abstract

PURPOSE:To reduce a production cost, by applying a reverse bias to a photoelectric conversion device so as to insulate a shorted place electrically (RB process), repairing the defective place, simultaneously performing RB at every stage in the case of an integrated structure, thereby making the time required for the RB process equal to the time in a single structure. CONSTITUTION:On a glass substrate 12, a first electrode 13 of ITO/SnO2, P-type a-SiC 14, I-type a-SiC 14 and N-type mu-C-Si 14 are formed. As a second electrode 15, a laminated electrode of ITO, Ag and Al is used. Such photoelectric conversion devices are integrated in 15 stages. The area of an element is, e.g., 69.83cm<2>. The yield rate of 50 elements having the efficiency of 7% or more in a structure before the RB is about 30%. A negative electrode is connected to the P-type a-SiC 13, and a positive electrode is connected to the N-type mu-C-Si 15 in the RB. The output of a power source 16 is gradually increased and up to 8V is applied to the element of one stage. At this time, an RB end point, at which a current is suddenly stopped to flow, is located in the vicinity of 4-6V in many cases.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a photoelectric conversion device using a non-single-crystal semiconductor, in which holes or pinholes are inadvertently formed in the semiconductor layer when forming the non-single-crystal semiconductor layer. A method for producing a photoelectric conversion semiconductor characterized by repairing a photoelectric conversion device in which a first electrode and a second electrode of the conversion device are short-circuited or leaked to each other through these holes or pinholes. It is something.

"Prior Art" Conventionally, photoelectric conversion devices have mainly used non-single crystal semiconductors having PIN junctions with a small area of several Cd. Recently, there have been attempts to produce photoelectric conversion devices with a large area of several 1000 cJ and to lower the manufacturing cost per unit area. However, such photoelectric conversion devices have holes in a part of the non-single crystal semiconductor layer.

It always has pinholes, cracks, etc., and these parts become short circuit current parts (short circuits) or weak leak parts. Fill factor (F F
) causes a severe decrease in energy conversion efficiency,
The manufacturing yield was poor, and as a result, it was extremely difficult to reduce the manufacturing cost per unit area.

Therefore, when manufacturing a large-area photoelectric conversion device, there is a need for a method of selectively removing only the current short-circuit portion. As a representative example, Japanese Patent Laid-Open No. 60-46080 is shown. This invention is characterized in that an electrode is formed on a semiconductor having a PIN junction, the surface of the electrode is immersed in an etching solution, and a current is applied to selectively remove only the current short-circuit portion. The solution used for this purpose is an etching solution, a specific example of which is given in Specification 3.
It is shown in the upper left column ffL9 to the lower right column 1, 1 on page 76.

According to this method, ITO on a short-circuited semiconductor is selectively removed by etching. 0 as an electrolyte for that purpose
．． A dilute solution of 0.01 to 1 χ hydrogen chloride and 0.05 mol NaCl salt is used.

However, in such an electrolyte ITO and the show 1 below
Previously known methods of removing semiconductors in ~ parts have a number of other drawbacks. That is, this removed area must be selectively coated with an insulator in a subsequent process. Furthermore, since the non-single crystal semiconductor layer was immersed in acidic water overnight, metal coatings and the like had to be formed after this process was completed. Further, during this step, a step is required to sufficiently remove impurity ions, moisture, etc. adsorbed on the semiconductor layer, which increases manufacturing costs.

``Object of the Invention'' In order to eliminate these drawbacks, the present invention does not remove short-circuited parts by wet etching, but rather applies reverse bias to the photoelectric conversion device to electrically insulate the shorted parts ( Hereinafter, this process will be referred to as performing RB). In other words, the defect is repaired by applying a negative voltage to the electrode on the P-type non-single crystal semiconductor layer side of the photoelectric conversion device and a positive voltage to the electrode on the N-type non-single crystal semiconductor layer side.

The present invention will be explained below with reference to the drawings.

FIG. 1 shows an overview of the invention. For ease of understanding, the photoelectric conversion device has a PIN structure using an amorphous silicon semiconductor.

The structure is a glass substrate (1), a first electrode (2) P type a
-3i (3), type I a-5i (4), type N a-3t (
5), the second electrode (6). The present invention is not particularly limited to this structure. A power source (7) is connected so that a negative voltage is applied to the first electrode (2) and a positive voltage is applied to the second electrode (6). The graph in FIG. 2 shows the relationship between the current flowing through the circuit and the voltage when the output of the power supply (7) is increased slowly and continuously from OV to about 8V.

In FIG. 2(a), the solid line (10) indicates that the applied voltage is approximately 5
．． Up to around 5V, the current increases as the voltage increases. The resistance value from 0 to 1 Ω is very small, 8.6Ω, and it can be easily imagined that a short circuit current portion (8) exists in the semiconductor layer of the photoelectric conversion device. Suddenly the current stops flowing. Thereafter, even if a voltage is applied up to about 8V, the current remains almost constant. The resistance value at this time was approximately 800 Ω, which was 90 times higher than when the voltage was 0 to 1 V. After this, even if a reverse bias voltage is applied to this photoelectric conversion device again, the result shown in FIG. 2(b) is
As shown by the solid line (11), the resistance value is almost constant and the current does not flow suddenly.It varies depending on the characteristics of each photoelectric conversion device, but when 8V is applied, the current is 15V at maximum.
mA L, or current does not flow. The resistance value is 500Ω
That was it. In other words, while applying a voltage from ○■ to 5.5V, current flows only to the short-circuit current portion formed by holes or pinholes in the semiconductor layer, and the short-circuit current portion is burnt out or Since it is electrically insulated, no abnormal current will flow even if voltage is applied again.

Generally, when a reverse bias voltage (RB) is applied to a device with diode characteristics, such as a photoelectric conversion device, to an extent that does not destroy the device, it exhibits a high resistance (say Ro) and a current flows as shown in Figure 1. There's nothing wrong. Now, if there is a short circuit current part (short) due to a pinhole in the semiconductor layer, the resistance value of that part (for example, R1 + R21'
-'Rn. ) is clearly small, Re ＞ ＞
RIR2...Rn. At this time, the current selectively flows through the short circuit current section with low resistance. Since these holes or pinholes are generated by dust, flakes, etc. during the formation of the semiconductor layer, the area of the short circuit current portion is extremely small. Therefore, the current flows through this small area, which generates heat, and the material that locally becomes very hot and forms a short circuit current section.
The reasons for this are not clear, such as burnout, vaporization, oxidation of the surface, and elution, but the result is insulation.For this reason, a photoelectric conversion device that has undergone RB once has no parallel resistance. This increases the open-circuit voltage and improves the energy conversion efficiency.The reverse bias voltage applied when performing RB can be of any form as long as it can cause excessive current to flow into the defective area. But that's fine.

Examples are shown below. Note that the present invention is not limited only to the examples.

Example 1 The photoelectric conversion device used in this example is a glass substrate (1) having almost the same structure as that shown in FIG.
First electrode (2) of O-5nOz, P type a-3iC
(3) Type I a-5i (4), Type N μmC-5i
(5), and as the second electrode (6), ITO and A
A laminated electrode of g and Ill is used. This photoelectric conversion device was not integrated and had an element area of 4.59 cn+. Before performing RI3, the photoelectric conversion device 150 with this structure
The energy conversion efficiency of individual devices varies widely, ranging from 3 to 10χ (the yield of devices with an efficiency of 7% or more was about 30χ).

RB is performed on 150 such samples by the method shown in FIG. That is, I on the P type a-5iC (3) side
The negative electrode for TO, 5nOz (2) is N-type p-C-
A positive electrode was connected to the ITO-Ag-AI (6) on the 3i (5) side, and the output of the power source (7) was gradually increased, up to 8 V in this example. At this time, 5 in Figure 2
．． There were many points (referred to as RB end points) where the current suddenly stopped flowing on the circuit, such as around 5V, around 3 to 5V.

Table 1 shows the results of performing RB on 150 pieces. Shown below.

Table 1゜Table 1. , Rsh indicates the resistance value when a reverse bias voltage of IV is applied to the photoelectric conversion device.

Example 2: The photoelectric conversion device used in this example is an I/O converter on a glass substrate (1) having a structure similar to that shown in FIG.
TO-5nOz first electrode (2), P-type a-5i (3
) I-type a-3i (4) and N-type a-3i (5) are formed, and A1 is used as the second electrode (6). The rest is almost the same as in Example 1. R about 150 pieces
FIG. 5 shows the typical characteristics of the photoelectric conversion device before and after R8. The curve (22) is the characteristic before RB, and the curve (23) is after RB. Raw data are shown in Table 2.

Table 2 In this way, it is possible to repair a device that is almost unusable into a completely usable device, and the time required to perform RB on one sample and repair it is: It only took about 10 to 20 seconds. and 1
Table 3 shows the characteristics of the 50 samples before and after R8.

Table 3 Example 3 The photoelectric conversion device used in this example consisted of a glass substrate (12) having almost the same structure as that shown in FIG. 3(a).
On top, a first electrode (13) of ITO/5nOz, P type a
-5iC (14), type I a-5i (14), type N, c
rc-Si (14), and a second electrode (15)
As such, a laminated electrode of ITO, Ag, and AI is used.

This photoelectric conversion device is integrated into 15 stages and has an element area of 69.83 cm! Met. Before performing RB, the yield of elements having an efficiency of 7% or more was about 30x for 50 photoelectric conversion devices of this structure.

RB is performed on 50 such samples by the method shown in FIG. In other words, ITO-s on the P type a-3ic side
Connect the negative electrode to noz (13) and the positive electrode to ITO-Ag-AI (15) on the N-type u-C-3i side, and gradually increase the output of the power source (16). In this example, up to 8V was applied to one stage of elements. At this time, there were many points (referred to as RB end points) around 4 to 6 V where the current suddenly stopped flowing on the circuit, such as around 5.5 V in FIG. Table 4 shows the results of performing RB on 50 pieces.

Table 4 As described above, the conversion efficiency after RB was very good, and there was almost no variation, and all 50 samples were within 9.5 ±5z.

Example 4 The photoelectric conversion device used in this example had a first electrode (18) of MO on a glass substrate (17) having almost the same structure as that shown in FIG. Type a-5i (19
), type I a-3i (19), type P a-3i (19
), and ITO is used as the second electrode (20). The rest is almost the same as in Example 3. RB was performed on 50 photoelectric conversion devices, and the typical characteristics of photoelectric conversion devices around R8 are shown in FIG. The curve (24) is the characteristic before RB, and the curve (25) is after RB.

The raw data for this sample is shown in Table 5.

Table 5 As described above, the characteristics of FF (fill factor) are particularly improved, leading to an improvement in conversion efficiency. Table 6 shows the characteristics of the 50 samples before and after R8.

Table 6 In this example, RB was performed on all 15 stages at the same time. When performing this process, it is possible to provide a power supply for each stage of the photoelectric conversion device as in this embodiment, or apply a reverse bias voltage to all 15 stages, so that each stage is provided with a power supply on the circuit to prevent the elements from being destroyed. You may try to come up with some ideas. Moreover, if RB is performed in 15 stages at the same time, it is possible to shorten the time and is effective in reducing production costs.

Example 5 Using samples with exactly the same structure as in Example 1, after performing RB on 50 samples, the characteristics of the photoelectric conversion device were immediately measured without removing the connection terminal for RB. That is, a negative electrode is attached to the electrode (2) on the P-type semiconductor layer side of the sample,
Conversely, connect the positive electrode to the electrode (6) on the N-type semiconductor layer side,
After performing RB on the photoelectric conversion device in the same manner as in Example 1 to improve the bond pair and yield of the photoelectric conversion device, the polarity of the electrode was reversed without disconnecting the electrode, and the polarity was reversed to measure the photoelectric conversion efficiency. light, in this example A M 1 (10
The sample was irradiated with 0 mW/cn, and the characteristics of the photoelectric conversion device were measured. At this time, the polarity of the electrodes may be reversed by operating the power supply or by switching the circuit.

Since RB and characteristic measurements can be performed continuously and almost simultaneously as in this embodiment, it has become possible to significantly reduce the cost of producing a photoelectric conversion device.

As shown in the embodiments above, according to the present invention, a photoelectric conversion device that would conventionally be discarded as a defective device can be repaired to a fully usable device.

Furthermore, for non-defective products, it was possible to eliminate variations in product characteristics, and the yield rate was significantly improved.

In addition, in the photoelectric conversion device that underwent RB once, the defective parts were completely repaired, so the characteristics did not deteriorate again.

Furthermore, since the process is carried out after the manufacturing of the photoelectric conversion device is completely completed, the yield of the product can be improved without changing the conventional manufacturing process at all.

According to the present invention, since the parallel resistance component of the photoelectric conversion device is increased, in the case of an integrated photoelectric conversion device, the FF is particularly improved and the conversion efficiency is improved.

Furthermore, in the case of an integrated structure, since RB can be performed between each stage, the time required for the RB process is exactly the same as in the case of a single structure. Additionally, since the RB process and the photoelectric conversion device characteristic measurement process can be performed simultaneously, production costs can be reduced.

The present invention is not limited to the embodiments, but can be applied to elements with a wide range of structures.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an outline of the present invention. FIG. 2 shows the current value flowing through the photoelectric conversion device when a reverse bias is applied before and after R8 of the present invention. FIG. 3 shows a schematic diagram of the invention in the case of an integrated photoelectric conversion device. FIG. 4 is a graph showing the maximum current voltage at the end point of RB. FIG. 5 and FIG. 6 show the characteristics of the photoelectric conversion device before and after R8.

Claims (1)

[Claims] 1. A PIN having a plurality of photoelectric conversion regions on a substrate having a conductive surface, and electrically connecting the photoelectric conversion regions in series.
Alternatively, a method for producing a photoelectric conversion device having a non-single-crystal semiconductor layer having at least one NIP junction, wherein a reverse bias voltage is applied to both ends of the non-single-crystal semiconductor layer of each photoelectric conversion region, and the non-single-crystal semiconductor layer is 1. A method for manufacturing a photoelectric conversion device, comprising the step of simultaneously repairing a defective portion of a layer in all of a plurality of photoelectric conversion regions. 2. The method of manufacturing a photoelectric conversion device according to claim 1, wherein a current of 15 mA or more does not flow even if a reverse bias voltage of 8 V is applied to each photoelectric conversion region after the repair step is completed.