JPH0568866B2 - - Google Patents

Description

Detailed Description of the Invention "Industrial Application Field" The present invention provides a P-type region that serves as a + electrode and an N-type region that serves as a - electrode only on one main surface of a semiconductor provided on a substrate.
The present invention relates to a photoelectric conversion device that is easy to manufacture and has a simple structure by selectively providing mold regions.

"Conventional technology" Conventionally, photoelectric conversion devices used PN or PIN.
2. Description of the Related Art Solar cells or photocells in which a junction is formed on a single crystal silicon substrate are known. But this PN
Alternatively, a PIN junction has positive or negative electrodes on the front and back surfaces of a single-crystal silicon substrate, and the bonding surface is provided substantially parallel to the main surface of the substrate, and a large amount of light is irradiated onto this bonding surface. It was simply a matter of devising a way to make it work.

``Problems to be solved by the invention'' These conventional photoelectric conversion devices had a bonding surface parallel to the main surface of the semiconductor substrate, so the direction in which the electric field was applied was perpendicular to the light irradiation surface, resulting in light irradiation intensity. The electric field was not uniform in the direction in which it was applied, and it was not possible to efficiently generate electrons and holes.

In addition, single crystal substrates have many drawbacks, such as being extremely easily cracked and expensive, difficult to process, and unable to integrate photoelectric conversion devices and arrange a plurality of them in series or parallel.

The present invention aims to efficiently generate electrons and holes in a non-single-crystal semiconductor, and also to make it easier to process the semiconductor into a non-single-crystal semiconductor.

"Means for Solving the Problems" The present invention provides a P-type region and an N-type region at least in the upper part of a non-single crystal semiconductor provided on a surface opposite to the light incident surface of a transparent substrate. The above object has been achieved by a photoelectric conversion device characterized by selectively disposing parallel to the light irradiation surface.

``Action'' With the above structure, that is, from the same light irradiation surface, P
By forming the type region and the N type region in the depth direction of the semiconductor, the light intensity in the electric field direction between the P type region and the N type region becomes constant. Another attempt was made to improve the photoelectric conversion efficiency by making the junction surface between the P-type region or the N-type region and the intrinsic semiconductor layer extremely narrow and reducing the rate of carrier recombination at the junction interface.

The present invention will be described below with reference to Examples.

``Example'' FIG. 1 is a longitudinal sectional view showing the manufacturing process of the present invention. In FIG. 1A, substrate 1 is a conductive or insulating substrate. The requirements for this substrate are that it is inexpensive and has mechanical strength and heat resistance for the subsequent film forming process. Therefore, in this example, a glass substrate was mainly used. Plasma is applied to the upper surface of this substrate 1 at a temperature of room temperature to 500°C.
By CVD method, SiH4: 20SCCM, pressure: 0.01~
Deposition was performed for about 60 minutes at 0.3 TORR, and the first semiconductor 43 with an energy band width of about 2.3 eV and a film thickness of 2500 Å was deposited.
was formed. At this time, if necessary, add C to the raw material gas.
The energy band width was changed by adding 5 to 50 atm% of O and N. Furthermore, the second semiconductor 2 was formed on this first semiconductor 43. At this time, a gas containing C, O, and N was added to the raw material gas as necessary to change the energy band width, and a second semiconductor having an energy band width of 1.6 ev and a film thickness of 1 μm was formed.

Furthermore, a third semiconductor 3 was formed on the second semiconductor 2 under the same manufacturing conditions as the first semiconductor 43.

These first semiconductor, second semiconductor and third semiconductor
The semiconductor was essentially an intrinsic semiconductor unless P-type or N-type dopants were added.

Next, after etching this semiconductor so as to leave only the portion necessary for the photoelectric conversion device, an insulating film having a masking effect on the third semiconductor is formed on the upper surface and around the sides of the semiconductor layer using, for example, silicon oxide or Plasma silicon nitride to a thickness of 500-2000Å
Formed by CVD method. In this example, SiH ₄ ,
A silicon nitride film was formed using _NH3 .

Furthermore, as shown in FIG. 1B, openings 7 and 8 were formed by selectively removing the insulating film 4 in the portions that would become the + and - electrodes by photo-etching. The width of this opening was narrowed to 2 to 20 μm, especially 5 to 7 μm, and was shaped like a comb, and the distance 11 between the openings 7 and 8 was approximately the same as the film thickness of the second semiconductor. It is preferable that the diffusion length be 1/4 to 1/2 shorter than the diffusion distance of electrons and holes generated by re-excitation of the .

Next, dopants such as boron B and phosphine P are doped through the openings 7 and 8 to a concentration of 10 ¹⁸ cm ^-3 to 3 mol % by diffusion, ion implantation, etc., as shown in Figure 1C. Region 9 and N-type region 10 were formed in the third semiconductor layer.

Next, as shown in FIG. 1D, aluminum is vapor-deposited to a thickness of 1 μm on the upper surface of each of the P-type region 9 and the N-type region 10 to form an ohmic contact electrode 14 and an external connection terminal 16 extending therefrom on the substrate. 17 was formed.

When the energy band diagram is considered along the dashed line A-A' in FIG. 1D, FIG. 2A is obtained as an example thereof. + electrode 14, P-type region 9,
a substantially intrinsic third semiconductor 2N type region 10;
- 14, 9, 2, 1 corresponding to electrode 15, respectively;
0,15 are written.

As is clear from this Figure 2 A, there are 14 holes.
The electrons also diffuse to 15, and if some of the holes diffuse to 10, they are repelled - prohibiting recombination near the electrode. A similar thing happens with the + electrode.

In the present invention, the semiconductor material may be not only a silicon-containing semiconductor but also a - group or - group compound semiconductor, and if its structure is also non-single crystal,
It may be so-called amorphous, semi-amorphous, or polycrystalline, and its production method may be a known chemical vapor phase reaction method.

In addition, in this embodiment, up to the third semiconductor
Although the layers are stacked, the semiconductor layer may be one or two layers.

``Effects of the Invention'' The present invention is a photoelectric conversion device typically having a structure as shown in Figure 1D. The direction of the electric field generated between the P-type region and the N-type region is parallel to the light irradiation surface, and the junction surface between the P-type or N-type region and the intrinsic semiconductor layer is narrow, so carrier regeneration at the junction interface is prevented. Since it was possible to reduce coupling, it was a highly efficient photoelectric conversion device.

Also, by making the semiconductor non-single crystal, it has become easier to process the semiconductor.

Other features include the provision of external lead-out electrodes on the substrate, which allows multiple photoelectric conversion devices to be integrated on one substrate and connected in series or parallel, and backflow prevention diodes can also be connected on the same substrate. It can be made from semiconductors.

Since the electrode is formed only on one surface, there is no need to consider thermal stress during semiconductor manufacturing.

The structure is extremely simple, and since the top and sides of the semiconductor are covered with a silicon nitride film, it has excellent reliability against external contamination.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the manufacturing process of a photoelectric conversion device having a structure according to the present invention. FIG. 2 is an energy band diagram of FIG. 1D. DESCRIPTION OF SYMBOLS 1...Substrate, 2...First non-single crystal semiconductor, 3
...Second non-single crystal semiconductor, 4...Insulating film.

Claims (1)

[Claims] 1. An intrinsic or substantially intrinsic semiconductor is provided, and a P-type semiconductor region and an N-type semiconductor region are arranged only on one main surface side of the semiconductor so as to be shorter than the diffusion distance of electrons and holes and spaced apart from each other. , irradiating light onto the other main surface opposite to the one main surface to collect electrons and holes generated in the intrinsic or substantially intrinsic semiconductor in the N and P type semiconductor regions; A photoelectric conversion device characterized by: