Rod-shaped semiconductor device

A rod-shaped semiconductor device having a light-receiving or light-emitting function is equipped with a rod-shaped substrate made of p-type or n-type semiconductor crystal, a separate conductive layer which is formed on a part of the surface of the substrate excluding a band-shaped part parallel to the axis of the substrate and has a different conduction type from the conduction type of the substrate, a pn-junction formed with the substrate and separate conductive layer, a band-shaped first electrode which is formed on the surface of the band-shaped part on the substrate and ohmic-connected to the substrate, and a band-shaped second electrode which is formed on the opposite side of the first electrode across the shaft of said substrate and ohmic-connected to the separate conductive layer.

TECHNICAL FIELD

The present invention relates to a semiconductor device, especially a semiconductor device which is made of a rod-shaped semiconductor crystal and has a light-receiving or light-emitting function.

BACKGROUND OF THE INVENTION

The inventor of the present application proposed, in U.S. Pat. No. 6,204,545, a spherical semiconductor element which has a light-receiving or light-emitting function, wherein a spherical pn-junction is formed near the surface of a spherical semiconductor crystal, and dot-shaped positive and negative electrodes are formed at both ends across the center of the spherical crystal. The semiconductor element has optical symmetry in other directions than the axial direction connecting the pair of electrodes, and has the advantage that it can receive light three-dimensionally from various directions and emit light three-dimensionally in various directions.

The inventor of the present application proposed, in International Laid-Open Patent Application WO03/017382, a spherical semiconductor device which is nearly the same semiconductor element as said semiconductor element, wherein one electrode is formed on a flat surface with a part of an apex of a spherical semiconductor crystal removed, and the other electrode is formed on the opposite side of the electrode across the center of the semiconductor crystal.

A light-receiving or light-emitting module is obtained by arranging such spherical semiconductor elements in a planar matrix form with many rows and columns, serially connecting multiple semiconductor elements in each column, and connecting in parallel multiple semiconductor elements in each row. The larger the light-receiving area or light-emitting area of the module is made, the larger the number of connecting points at which the semiconductor element is electrically connected becomes.

The inventor of the present application proposed, in International Laid-Open Patent Application WO02/35612, a spherical semiconductor device which is nearly the same semiconductor element as said semiconductor element, wherein a pair of flat surfaces are formed by removing both ends across the center of a spherical semiconductor crystal, a pn-junction is formed near the surface including one flat surface of the semiconductor crystal, and positive and negative electrodes are formed on the one flat surface and the other flat surface.

In addition, proposed in International Laid-Open Patent Application WO02/35612 is a rod-shaped semiconductor element which has a light-receiving or light-emitting function, wherein a pair of end surfaces is formed perpendicular to the shaft on a columnar semiconductor crystal, a pn-junction is formed near the surface of the semiconductor crystal including one end surface, and positive and negative electrodes are formed on both of the end surfaces. The rod-shaped semiconductor element has an optical symmetry in other directions than the axial direction connecting the pair of electrodes, and has an advantage that it can receive light three-dimensionally from various directions and emit light three-dimensionally in various directions.

In the photovoltaic array described in U.S. Pat. No. 3,984,256, an n-type diffusion layer is formed on the surface of a filament made of p-type silicon semiconductor of 0.001˜0.010 inches in diameter, a plural number of this filament are arranged in parallel and in a planar form, multiple P-connection line members and N-connection line members are alternately placed orthogonally on the top of these filaments, the P-connection line member is ohmic-connected to the exposed part of the p-type silicon semiconductor of multiple filaments, the N-connection line member is ohmic-connected to the n-type diffusion layer of multiple filaments, multiple P-connection line members are connected to a P bus, and multiple N-connection line members are connected to an N bus. An insulating fiber with a superior strength is woven in so as to constitute multiple P buses and N buses and a mesh, thus constituting a flexible solar battery blanket which generate electricity by receiving incident light from its top surface.

In the semiconductor fiber solar battery and module described in U.S. Pat. No. 5,437,736, a molybdenum conductive layer is formed on the surface of an insulating fiber, two layers of p-type and n-type thin-film semiconductor layers having a photovoltaic function and a ZnO conductive layer are formed on approximately ⅗ of the periphery of the surface of this conductive layer, a plural number of these semiconductor fiber solar batteries are arranged in parallel and in a planar form, a metal coating is formed on its backside, after which the metal coating is partially removed in a specified pattern, thus forming a connection circuit which performs tasks such as serially connecting multiple semiconductor fiber solar batteries.

Patent Document 2: International Laid-Open Patent Application WO03/017382.

Patent Document 3: International Laid-Open Patent Application WO02/35612.

In manufacturing a solar battery panel using spherical semiconductor elements, a near-spherical semiconductor elements with a flat surface formed on a part of each, or near-spherical semiconductor elements with a pair of flat surfaces formed, the number of connecting points which electrically connect the semiconductor elements increases, the structure of a conductive connection mechanism which electrically connects the semiconductor elements becomes complex, and its manufacturing cost increases.

Because said rod-shaped semiconductor element also has a granular shape, in manufacturing a solar battery panel, the number of connecting points which electrically connect the semiconductor elements increases, the structure of a conductive connection mechanism which electrically connects the semiconductor elements becomes complex, and its manufacturing cost increases.

Furthermore, because a pair of electrodes are formed on both end surfaces perpendicular to the shaft, if the length of the rod-shaped semiconductor element is made large, the distance between the positive and negative electrodes increases, and the electrical resistance between the positive and negative electrodes increases. Therefore, the rod-shaped semiconductor element is not fit for manufacturing a semiconductor element having a length multiple times that of the diameter.

Because the photovoltaic array described in U.S. Pat. No. 3,984,256 has a construction wherein light enters from the top in the same manner as solar battery panels installed near-horizontally, it cannot receive light entering from both sides of the panel. This is also true with the semiconductor fiber solar battery in U.S. Pat. No. 5,437,736.

Especially, in a solar battery panel embedded in a window glass for example, it is desired that it be able to receive light from both sides. On the other hand, in constructing a light-emitting panel with semiconductor elements having a light-emitting function, it is desirable that light can be emitted to both sides of the panel.

Objectives of the present invention include providing a rod-shaped semiconductor element which has a light-receiving or light-emitting function and can increase the light-receiving area without increasing the inter-electrode distance, providing a rod-shaped semiconductor element which has a large length/diameter ratio and can reduce the number of electrical connecting parts in making a panel of multiple semiconductor elements, providing a rod-shaped semiconductor element which is hard to roll, providing a rod-shaped semiconductor elements wherein polarity of each electrode is easy to identify, and so on.

The rod-shaped semiconductor device of the present invention, having a light-receiving or light-emitting function, comprises a rod-shaped substrate made of p-type or n-type semiconductor crystal having a circular cross section or near-circular cross section, a separate conductive layer which is formed on a part of a surface of the substrate excluding a band-shaped part parallel to an axis of the substrate and has a different conduction type from that of the conduction type of the substrate, a near-cylindrical pn-junction formed with the substrate and the separate conductive layer, a band-shaped first electrode which is ohmic-connected to a surface of the band-shaped part of the substrate, and a band-shaped second electrode ohmic-connected to the separate conductive layer on an opposite side of the first electrode across the axis of the substrate. The separate conductive layer may be formed by diffusion, film formation, or ion injection.

If the rod-shaped semiconductor device has a light-receiving function, when sunlight is received, it generates a photovoltaic power of a specified voltage by its pn-junction, and outputs it between the first and second electrodes. Because it has a light-receiving symmetry about a plane which includes the first and second electrodes, light beams entering from both sides of the plane are received to generate electric power. If a large number of rod-shaped semiconductor devices are arranged in a panel shape and a circuit to extract the output is formed, it becomes a solar battery panel (solar battery module).

If the rod-shaped semiconductor device has a light-emitting function, when a specified voltage is applied between the first and second electrodes, light corresponding to the band-gap energy from the pn-junction is emitted from the pn-junction. If a large number of rod-shaped semiconductor devices are arranged in a panel shape and a circuit to apply a voltage is formed, it becomes a light-emitting panel (light-emitting module).

According to the rod-shaped semiconductor device of the present invention, because band-shaped first and second electrodes connected to the surface of a band-shaped part of a rod-shaped substrate and a separate conductive layer are installed, even when the length/diameter ratio of the substrate is increased, the distance between the first and second electrodes can be maintained smaller than the diameter of the substrate, and the electrical resistance between the first and second electrodes can be maintained small. Therefore, power generating performance or light-emitting performance in the pn-junction can be maintained high.

As a result, in constructing a light-receiving or light-emitting panel, the light-receiving area of each semiconductor device is increased by increasing the length/diameter ratio of the substrate, and the number of electrical connecting parts for wiring the semiconductor devices can be decreased, making it possible to improve the reliability of the panel and reduce the manufacturing cost. Furthermore, because there is a light-receiving or light-emitting symmetry about a plane including the first and second electrodes, it is possible to construct a light-receiving panel which can receive light from both sides of the panel or a light-emitting panel which can emit light from both sides of the panel.

As the constitutions of dependent claims of the present invention, various kinds of constitutions such as the following may be adopted.

(1) A band-shaped apex of the substrate is removed to form a band-shaped flat surface, and on this flat surface the band-shaped part is formed, not only making it a rod-shaped semiconductor element which is hard to roll, but also making it possible to easily identify the polarities of the first and second electrodes.
(2) An antireflective film is formed on a part of the surfaces of the substrate and separate conductive layer excluding the first and second electrodes.
(3) The substrate is made of p-type Si single-crystal or Si polycrystalline, and the separate conductive layer is made of an n-type conductive layer containing P, Sb, or As.
(4) The substrate is made of n-type Si single-crystal or Si polycrystalline, and the separate conductive layer is constituted of a p-type conductive layer containing B, Ga, or Al.
(5) The device is constructed to be a light-receiving device which receives light and generates electricity.
(6) The substrate is made of n-type GaP single crystal or GaAs single crystal, and the separate conductive layer is constituted of an n-type diffusion layer wherein Zn is thermally diffused, which constitutes a light-emitting diode.
(7) The substrate is made of n-type GaAs single crystal, and the separate conductive layer is formed by diffusion, film-forming, or ion-injection of p-type GaAs, which constitutes a light-emitting diode.
(8) The substrate is made of n-type SiC single crystal, and the separate conductive layer is formed by forming a p-type GaN, GaInP, or P film, which constitutes a light-emitting diode.
(9) The area of the pn-junction is set larger than the area of a cross section perpendicular to the axis of the substrate.

DESCRIPTION OF NUMERALS

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The rod-shaped semiconductor device of the present invention, having a light-receiving or light-emitting function, comprises a rod-shaped substrate made of p-type or n-type semiconductor crystal, a separate conductive layer which is formed on a part of a surface of the substrate excluding a band-shaped part parallel to the axis of the substrate and has a different conduction type from that of the substrate, a pn-junction formed with the substrate and the separate conductive layer, a band-shaped first electrode which is formed on the surface of the band-shaped part of the substrate and ohmic-connected to the substrate, and a band-shaped second electrode which is formed on the opposite side of the first electrode across the axis of the substrate and ohmic-connected to the separate conductive layer.

An embodiment of the present invention will be explained based on the drawings.

The rod-shaped semiconductor device20(seeFIGS. 17 and 18) of the present invention is a rod-shaped semiconductor device (solar battery cell) having a light-receiving function. The structure of this rod-shaped semiconductor device20will be explained while explaining its manufacturing method.

As illustrated inFIGS. 1 and 2, first manufactured is a rod-shaped silicon single crystal body1which is similar to a line member of a small diameter. The diameter of this silicon single crystal body1is about 2.0 mm for example, and the length of the silicon single crystal body1is 60˜300 mm. In manufacturing this silicon single crystal body1, molten silicon is extracted through a small-diameter hole on the bottom of a crucible made of graphite or quartz. When starting this extraction, a small piece of silicon single crystal is used as a seed crystal to manufacture the silicon single crystal body1of a small-diameter rod shape continued from the seed crystal. This kind of manufacturing method of the rod-shaped single crystal body1is described in a literature such as Jpn. Appl. Phys. Vol. 35 (1996) pp. L793-795.

Next, as illustrated inFIGS. 3 and 4, by polishing the silicon single crystal body1using a polishing machine and an appropriate abrasive material, it is made into a rod-shaped silicon single crystal body having a perfectly circular cross section perpendicular to the axis and a diameter of 1.8 mm, and a band-shaped flat surface2of 0.6 mm in width for example extending over the entire length is formed by polish-removing a band-shaped part on one spot in the circumference direction. In this manner, a rod-shaped continuous substrate3made of p-type silicon single crystal is manufactured. This flat surface2will be utilized in later processes as a reference surface for positioning and as a surface to prevent the continuous substrate3from rolling, and further utilized for identifying the polarities of positive and negative electrodes9A and10A described later.

Next, the continuous substrate3is thermally processed in an oxygen-containing gas using a publicly-known method to form a thermally-oxidized film4as illustrated inFIGS. 5 and 6over the entire surface of the continuous substrate3. A part of this thermally-oxidized film4will be used as a diffusion mask4ain thermally diffusing an n-type impurity in the later diffusion process.

Next, a part of the thermally-oxidized film on the flat surface2and its both sides of the continuous substrate3are covered with wax for example, and the other part of the thermally-oxidized film4not covered with wax is removed through an etching process using a fluoride solution by a publicly-known method, forming a band-shape diffusion mask4aas illustrated inFIGS. 7 and 8. Next, in the diffusion process as illustrated inFIGS. 9 and 10, an n-type impurity phosphorus (P), arsenic (As), or antimony (Sb) is thermally diffused to form an n-type diffusion layer5of 0.5˜1.0 μm in thickness (this corresponds to the separate conductive layer of a different conduction type from the conduction type of the substrate) on the part of the surface of the continuous substrate3excluding the band-shaped part masked with the diffusion mask4a, forming a near-cylindrical pn-junction6.

This pn-junction6has a partial cylindrical shape (partial cylinder with a C-shaped cross section), which is a cylinder having as a center the axis3aof the continuous substrate3excluding the flat surface2and the adjacent parts on both sides of it. Whereas a silicon oxide film7containing phosphorus formed during the phosphorus diffusion process gets impurities such as cupper, iron, and gold (these reduce the lifetimes of carriers) during the thermal diffusion of phosphorus, because it has hygroscopicity, it is once completely removed through an etching process with a publicly-known etchant. In doing so, the diffusion mask4ais also removed.

Next, as illustrated inFIGS. 11 and 12, the rod-shaped continuous substrate3with the n-type diffusion layer5and the pn-junction6formed is cut into a short columnar body of about 5 mm in length using a cutting device such as a wire saw to make a rod-shaped substrate3A with the n-type diffusion layer5and the pn-junction6formed, and an antireflective film8and positive and negative electrodes9A and10A are installed on this substrate3A in the following manner. First, as illustrated inFIGS. 13 and 14, as an antireflective film8which prevents reflection of light entering from the exterior, an antireflective film8made of silicon oxide coating or silicon nitride coating as a passivation film on the silicon surface is formed over the entire surface of the rod-shaped substrate3A by a publicly-known thermal oxidation method.

Next, as illustrated inFIGS. 15 and 16, a positive electrode member9made of paste containing silver is printed in a band shape of about 0.4 mm in width on the surface of the central part of the flat surface2of the substrate3A, and a negative electrode member10made of conductive paste containing aluminum is printed in a band shape of about 0.4 mm in width on the apex in the opposite side of the positive electrode member9across the axis3aof the substrate3A on the surface of the n-type diffusion layer5.

Next, after drying the positive electrode member9and the negative electrode member10, they are burnt in an inert gas, so that the positive electrode member9and the negative electrode member10each penetrate the antireflective film8to have the positive electrode member9form a positive electrode9A electrically ohmic-connected to the silicon single crystal of the substrate3A and the negative electrode member10form a negative electrode10A electrically ohmic-connected to the n-type diffusion layer5. In this manner, a rod-shaped (near-columnar) semiconductor device20(solar battery cell) is obtained (seeFIGS. 17 and 18). In this semiconductor device2, the area of the pn-junction6is set significantly larger than the cross-sectional area of a cross section perpendicular to the axis3aof the substrate3A.

Illustrated inFIG. 19is a perspective view from above of the semiconductor device20. The pn-junction6is formed in parallel near the near-cylindrical surface of the substrate3A, the negative electrode10A is ohmic-connected to the central part in the width direction of the n-type diffusion layer5, the positive electrode9A which is placed on the opposite side of the negative electrode10A across the axis3aand placed on the central part in the width direction of the flat surface2of the substrate3A is ohmic-connected to a p-type silicon single crystal of the substrate3A, and the positive electrode9A and the negative electrode10A are connected to both ends of the pn-junction6.

Therefore, when sunlight11entering a region of the surface of the semiconductor device20excluding the positive electrode9A and the negative electrode10A is absorbed by the silicon single crystal constituting the substrate3A, carriers (electrons and positive holes) are generated, and electrons and positive holes are separated by the pn-junction6to generate a photovoltaic power of about 0.5˜0.6 V between the positive electrode9A and the negative electrode10A.

This semiconductor device20has a near-columnar rod shape, the positive and negative electrodes9A and10A are positioned on both sides of the axis3aof the substrate3A, wherein the positive electrode9A is positioned in the center of a p-type surface of the flat surface2, and the negative electrode10A is positioned in the center of an n-type surface of the diffusion layer5. Therefore, there is a light-receiving symmetry about a plane connecting the positive and negative electrodes9A and10A, and sunlight can be absorbed from both sides of that plane with a wide directivity and a high light-receiving sensitivity. Even if the direction of incident light changes, the light-receiving sensitivity never decreases.

As illustrated inFIG. 19, on an arbitrary plane intersecting perpendicularly with the axis3aof the substrate3A, because three different positions A, B, and C along the periphery have almost equal sums to the distances to the positive and negative electrodes9A and10A, namely (a+b)≅(a′+b′)≅(a″+b″), the distribution of optical current induced by carriers generated in the substrate3A made of silicon single crystal becomes uniform about the axis3aof the substrate3A, which can reduce the resistance loss due to bias. Note that the surface of the pn-junction6is protected with an insulating silicon oxide coating8on the circumference and the end face intersecting perpendicularly with the axis3a.

Furthermore, according to this semiconductor device20, because the band-shaped positive and negative electrodes9A and10A are installed opposing each other across the axis3aon the surface of the rod-shaped substrate3A, even if the length/diameter ratio of the substrate3A is increased, the distance between the positive and negative electrodes9A and10A can be maintained smaller than the diameter of the substrate3A, thus the electrical resistance between the positive and negative electrodes9A and10A can be maintained at a small value, and the photoelectric conversion performance at the pn-junction6can be maintained high.

As a result, in constructing a solar battery panel (or a solar battery module) using a large number of semiconductor devices20by increasing the length/diameter ratio of the substrate3A, the number of electrical connecting parts can be reduced, the reliability of the solar battery panel can be enhanced, and the manufacturing cost can be reduced. Furthermore, because it has a light receiving symmetry about a plane including the positive and negative electrodes9A and10A, a solar battery panel which can receive light from both sides of the panel can be constructed.

Because the flat surface2is formed on the substrate3A, the flat surface2can be used as a reference surface when manufacturing the semiconductor device20, the flat surface2can prevent the continuous substrate3and substrate3A from rolling, and the positive and negative electrodes9A and10A can be easily identified by a sensor of an automatic assembling device for example via the flat surface2. Then, because the antireflective film8is formed on the surface of the semiconductor device20, reflection of the incident light can be suppressed to increase the light-receiving efficiency, and the antireflective film8which also functions as a passivation film can protect the surface of the semiconductor device20and secure the durability.

Examples of partially changing said embodiment are explained.

1) Whereas the diameter of the substrate3A in above described embodiment was 1.8 mm, the diameter of the substrate3A is not limited to this but may be an arbitrary value of 0.5 mm or larger. In order to save the silicon single crystal raw material, it should desirably be 1.0˜2.0 mm.

In addition, whereas the length of the substrate3A in above described embodiment was 5.0 mm, the length of the substrate3A is not limited to this but may be about 2˜20 times the diameter of the substrate3A.

However, the area of the pn-junction6should be set larger than the area of the cross section perpendicular to the shaft of the substrate3A.

2) Whereas the width of the flat surface2in above described embodiment was 0.6 mm, the width of the flat surface2is not limited to this but may be set to about 0.4˜0.6 mm. Here, the flat surface2formed on the substrate3A is not indispensable but may be omitted. However, in that case, the positive electrode9A will come to have the same structure as the negative electrode10A, wherein the positive and negative electrodes9A and10A are positioned symmetrically about the shaft3a.
3) Whereas the substrate3A of the semiconductor device20(solar battery cell) was made of p-type Si single crystal in this embodiment, it may be made of p-type Si polycrystalline. The separate conductive layer for forming the pn-junction6in cooperation with the substrate3A may be constituted of an n-type conductive layer containing P, Sb, or As. This n-type conductive layer may be formed by thermal diffusion, CVD film formation, or ion injection.

Furthermore, the substrate may be made of n-type Si single crystal or Si polycrystalline. The separate conductive layer for forming the pn-junction6in cooperation with the substrate3A may be constituted of a p-type conductive layer containing p-type impurities Ga, B, and Al. This p-type conductive layer may be formed by thermal diffusion, CVD film formation, or ion injection. Note that the substrate3A may be made of semiconductor other than Si, a single crystal of Ge, GaSb, GaAs, InP, or SiC, or a multicompound semiconductor containing these.

A semiconductor device20B of this Embodiment 2 is a light-emitting diode which has a light-emitting function. As illustrated inFIGS. 20 and 21, this semiconductor device20B is equipped with a substrate3B, a flat surface2B, a diffusion layer5B, a pn-junction6B, a negative electrode9B, a positive electrode10B, and a passivation coating8B, constituted of the same structure as the semiconductor device20in above described embodiment. The substrate3B is made of single-crystal or polycrystalline of n-type GaP (gallium phosphide) which is 0.5 mm in diameter and about 5.0 mm in length for example. Note that the diameter only needs to be about 0.5˜1.0 mm, and the length is not limited to 5.0 mm, either.

By thermally diffusing zinc (Zn) on the surface layer of the substrate3B masked with a diffusion mask consisting of a silicon nitride film (Si3N4) similar to above described diffusion mask4a, the p-type diffusion layer5B is formed on the substrate3B in the same manner as above described diffusion layer5, and the near-cylindrical (partial cylindrical shape close to a cylinder) pn-junction6B is formed. The area of this pn-junction6B is set larger than the area of the cross section perpendicular to the axis of the substrate3B.

In the same manner as above described antireflective film8, the passivation coating8B made of TiO2for example is formed on the whole surface except the positive and negative electrodes10B and9B, and in the same manner as the positive and negative electrodes9A and10A of above described embodiment, the positive and negative electrodes10B and9B are installed, wherein the negative electrode9B is positioned in the center of the width direction of the flat surface2B and electrically ohmic-connected to n-type GaP of the substrate3B, and the positive electrode10B is installed on the opposite side of the negative electrode9B across the axis3bof the substrate3B and electrically ohmic-connected to the p-type diffusion layer5B.

In this light-emitting semiconductor device20B (light-emitting diode), when a forward electric current is let flow from the positive electrode10B toward the negative electrode9B, red light is emitted in the radial direction from the pn-junction6B at nearly the same intensity. In the same manner as above described semiconductor device20, it has a light-emitting symmetry about a plane including the positive and negative electrodes10B and9B, wherein the generated red light is emitted at an equal emission intensity in the radial direction with a wide directivity. Because the pn-junction has a partial cylindrical shape close to a cylinder, the generated red light passes perpendicularly the surface of the semiconductor element20B and is emitted to the exterior. Therefore, the internal reflection loss of light is reduced, and the light-emitting efficiency is improved. Then, because the distance between the positive and negative electrodes10B and9B can be maintained equal to or smaller than the diameter of the substrate3B, the electrical resistance between the electrodes10B and9B can be maintained low, and a high light-emitting performance can realized.

An example of partially modifying above described semiconductor device20B is explained below.

It is also possible to construct the above described substrate3B using various kinds of publicly-known semiconductor materials (For example, GaAs, SiC, GaN, and InP) so that various kinds of light beams are emitted.

A separate conductive layer of a different conduction type from the substrate3B which forms the pn-junction6B in cooperation with above described substrate3B may be formed by thermal diffusion of impurities, CVD film formation, or ion injection.

For example, a light-emitting diode may be constructed by constituting the substrate3B of an n-type GaAs single crystal and constituting said separate conductive layer of a diffusion layer with Zn thermally diffused.

In addition, a light-emitting diode may be constructed by constituting the substrate3B of an n-type GaAs single crystal and forming above described separate conductive layer by thermally diffusing, forming a film by CVD of, or ion-injecting p-type GaAs. Also, a light-emitting diode may be constructed by constituting the substrate3B of an n-type SiC single crystal and forming said separate conductive layer by coating P-type GaN or GaInP.

Illustrated inFIGS. 22 and 23is a series solar battery module30wherein a plurality of above described semiconductor devices20(solar battery cells) are connected in series arranged in a planar form with the conduction direction aligned to the column direction. Adjacent positive and negative electrodes9A and10A are electrically connected by alloying via a thin-plate bar31made of iron-nickel alloy having a thermal expansion coefficient similar to the thermal expansion coefficient of Si single crystal.

For example, the positive and negative electrodes9A and10A can be alloyed by interfacing the face joined with the positive electrode9A with an aluminum film containing 2% Si and the face joined with the negative electrode10A with a silver film containing 1% antimony in the thin-plate bar31.

In this series solar battery module30, the output voltage can be increased by increasing the number of solar battery cells connected in series. Sunlight from the front side and sunlight from the back side can be received with a high photoreceptive sensitivity. As illustrated inFIG. 24, an equivalent circuit30A of this solar battery cell module30is a circuit wherein multiple light-receiving diodes20A corresponding to the semiconductor device20(solar battery cell) are connected in series.

Illustrated inFIGS. 25 and 26is a serial-parallel type solar battery module40wherein a plurality of semiconductor devices20(solar battery cells) are arranged in a planar matrix form of multiple rows and multiple columns with the conduction direction aligned to the column direction, and these semiconductor devices20are connected in series and in parallel. The positive electrodes9A of multiple solar battery cells in each row and the negative electrodes10A of multiple solar battery cells20in each adjacent row are electrically connected by alloying via a continuous thin-plate bar41.

In this solar battery module40, multiple solar battery cells in each column are connected in series via multiple thin-plate bars41, and multiple solar battery cells20in each row are connected in parallel via a pair of thin-plate bars41on their both sides. This thin-plate bar41is the same as the thin-plate bar31, joining with the positive and negative electrodes9A and10A by the same alloying as mentioned earlier.

The thin-plate bar41is also joined with the positive and negative electrodes9A and10A of the solar battery cell in the row at one end and the row at the other end for electrically connecting them to an external output wire. As illustrated inFIG. 27, an equivalent circuit40A of this solar battery module40is the one, wherein light-receiving diodes20A corresponding to the solar battery cells20are arranged in a matrix form of multiple rows and multiple columns, connected both in series and in parallel. An output current according to the number of the solar battery cells20in the row direction is generated, and an output voltage corresponding to the number of solar battery cells20in the column direction is generated.

In this solar battery module40, because solar battery cells20of multiple rows and multiple columns are connected both in series and in parallel, even if a part of solar battery cells20stop their power generating function due to breakdown, broken wire, shadow, etc., photocurrent flows bypassing those failed solar battery cells20, therefore power generating functions of normal solar battery cells20will not be lost. Because the solar battery module40can receive light from both sides, it is preferably constructed as a solar battery panel embedded in the road sound insulation walls or a fence-shaped solar battery panel.

If this rod-shaped semiconductor device is a solar battery cell, a solar battery panel can be constructed with a large number of the semiconductor devices, and if the rod-shaped semiconductor device has a light-emitting function, it can be utilized as a single light-emitting diode or for making a light-emitting panel comprising multiple semiconductor devices.