JP2007324324A - Solar battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar battery with improved efficiency in converting light energy to electric energy. <P>SOLUTION: The solar battery comprises a first conductive semiconductor substrate 6a, a first electrode 2a provided on the first surface M1a of the semiconductor substrate 6a, a second conductive semiconductor region 8a provided on the second surface M2a of the semiconductor substrate 6a, a nano column region 9a being provided on the semiconductor region 8a and having a plurality of nano columns 10a comprising InGaN, an InGaN region 18a being provided on the nano column region 9a and being connected to the plurality of nano columns 10a, and a second electrode 24a provided on the InGaN region 18a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solar cell.

In recent years, solar cells that can efficiently convert light energy in the short wavelength region into electrical energy have been developed. For such a solar cell, a nitrogen compound semiconductor having a wide band gap is suitable. Patent Document 1 discloses a semiconductor element (solar cell) having a semiconductor region made of a gallium nitride compound.
JP 2001-1111074 A1

  However, a semiconductor region made of a gallium nitride compound has a relatively high dislocation density in the case of a bulk state. If the dislocation density is high, the conversion efficiency from light energy to electrical energy decreases. Then, this invention is providing the solar cell with which the conversion efficiency from light energy to electrical energy was improved.

  The present invention relates to a first conductivity type semiconductor substrate having a first surface and a second surface opposite to the first surface, a first electrode provided on the first surface, and a second electrode on the second surface. A semiconductor region of the second conductivity type provided, a nanocolumn region provided on the semiconductor region and having a plurality of nanocolumns made of InGaN, and an InGaN provided on the nanocolumn region and connected to the plurality of nanocolumns And a second electrode provided on the InGaN region, the semiconductor substrate and the semiconductor region form a first pn junction, and each of the plurality of nanocolumns includes one or more first conductivity type nanocolumns And the first conductivity type nanocolumn part and the second conductivity type nanocolumn part are provided in order from the semiconductor region to the InGaN region. First The InGaN region has a first InGaN portion connected to a plurality of nanocolumns, and a second InGaN portion provided on the first InGaN portion, and a second InGaN portion Part has a conductivity type different from that of the first InGaN part, the first InGaN part and the second InGaN part form a third pn junction, and the band gap of the material of the semiconductor substrate is that of the material of the nanocolumn It is different from the band gap.

  The solar cell of the present invention has a nanocolumn made of a gallium nitride compound. This nanocolumn has a lower dislocation density than a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Light is incident on the pn junction of each nanocolumn. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. The band gap of the semiconductor substrate material is different from the band gap of the nanocolumn material (InGaN). For this reason, the wavelength of light converted into electrical energy in the pn junction formed by the semiconductor substrate and the semiconductor region is different from the wavelength of light converted into electrical energy in the pn junction of the nanocolumn. Therefore, electrical energy can be extracted from light of different wavelengths. A plurality of pn junctions are provided in the nanocolumn. For this reason, the more pn junctions provided in the nanocolumn, the more sunlight can be converted into electrical energy.

  The present invention relates to a first conductivity type semiconductor substrate having a first surface and a second surface opposite to the first surface, a first electrode provided on the first surface, and a second electrode on the second surface. A semiconductor region of the second conductivity type provided; a nanocolumn region having a plurality of nanocolumns made of InGaN; and a second semiconductor layer provided on the nanocolumn region and connected to the plurality of nanocolumns. The semiconductor substrate and the semiconductor region form a first pn junction, and each of the plurality of nanocolumns includes one or a plurality of first conductivity type nanocolumn portions and one or a plurality of second conductivity types. The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion are provided in order from the semiconductor region toward the second electrode, and form a second pn junction, and the semiconductor Band material of substrate material It is different from the band gap of the nano-columns of material, characterized in that.

  The solar cell of the present invention has a nanocolumn made of a gallium nitride compound. This nanocolumn has a lower dislocation density than a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Light is incident on the pn junction of each nanocolumn. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. The band gap of the semiconductor substrate material is different from the band gap of the nanocolumn material (InGaN). For this reason, the wavelength of light converted into electrical energy in the pn junction formed by the semiconductor substrate and the semiconductor region is different from the wavelength of light converted into electrical energy in the pn junction of the nanocolumn. Therefore, electrical energy can be extracted from light of different wavelengths. A plurality of pn junctions are provided in the nanocolumn. For this reason, the more pn junctions provided in the nanocolumn, the more sunlight can be converted into electrical energy.

  The present invention relates to a first conductivity type semiconductor substrate having a first surface and a second surface opposite to the first surface, a first electrode provided on the first surface, and a second electrode on the second surface. A semiconductor region of the second conductivity type provided, a nanocolumn region provided on the semiconductor region and having a plurality of nanocolumns made of InGaN, and an InGaN provided on the nanocolumn region and connected to the plurality of nanocolumns And a second electrode provided on the InGaN region, the semiconductor substrate and the semiconductor region form a first pn junction, and each of the plurality of nanocolumns includes one or more first conductivity type nanocolumns And the first conductivity type nanocolumn part and the second conductivity type nanocolumn part are provided in order from the semiconductor region to the InGaN region. First Of forming a pn junction, the band gap of the material of the semiconductor substrate is different from the band gap of the nano-columns of material, characterized in that.

  The solar cell of the present invention has a nanocolumn made of a gallium nitride compound. This nanocolumn has a lower dislocation density than a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Light is incident on the pn junction of each nanocolumn. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. The band gap of the semiconductor substrate material is different from the band gap of the nanocolumn material (InGaN). For this reason, the wavelength of light converted into electrical energy in the pn junction formed by the semiconductor substrate and the semiconductor region is different from the wavelength of light converted into electrical energy in the pn junction of the nanocolumn. Therefore, electrical energy can be extracted from light of different wavelengths. A plurality of pn junctions are provided in the nanocolumn. For this reason, the more pn junctions provided in the nanocolumn, the more sunlight can be converted into electrical energy.

  The present invention relates to a first conductivity type semiconductor substrate having a first surface and a second surface opposite to the first surface, a first electrode provided on the first surface, and a second electrode on the second surface. A semiconductor region of the second conductivity type provided, a nanocolumn region provided on the semiconductor region and having a plurality of nanocolumns made of InGaN, and an InGaN provided on the nanocolumn region and connected to the plurality of nanocolumns And a second electrode provided on the InGaN region, the semiconductor substrate and the semiconductor region form a first pn junction, and each of the plurality of nanocolumns extends from the semiconductor region toward the InGaN region. The InGaN region has a first InGaN portion connected to the plurality of nanocolumns, and a second InGaN portion provided on the first InGaN portion. The first InGaN portion and the second InGaN portion form a second pn junction, and the band gap of the material of the semiconductor substrate is different from the band gap of the material of the InGaN region. It is characterized by that.

  The solar cell of the present invention has a nanocolumn made of a gallium nitride compound. This nanocolumn has a lower dislocation density than a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. The band gap of the semiconductor substrate material is different from the band gap of the InGaN region material (InGaN). For this reason, the wavelength of light converted into electrical energy in the pn junction formed by the semiconductor substrate and the semiconductor region is different from the wavelength of light converted into electrical energy in the pn junction of the nanocolumn. Therefore, electrical energy can be extracted from light of different wavelengths.

  The present invention relates to a first conductivity type semiconductor substrate having a first surface and a second surface opposite to the first surface, a first electrode provided on the first surface, and a second electrode on the second surface. A nanocolumn region having a plurality of nanocolumns made of InGaN, and a second electrode provided on the nanocolumn region and connected to the plurality of nanocolumns, each of the plurality of nanocolumns being one or more The first conductivity type nanocolumn portion and one or a plurality of second conductivity type nanocolumn portions, and the first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion are connected from the semiconductor substrate to the second electrode. And a pn junction is formed.

  The solar cell of the present invention has a nanocolumn made of a gallium nitride compound. This nanocolumn has a lower dislocation density than a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Light is incident on the pn junction of each nanocolumn. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. A plurality of pn junctions are provided in the nanocolumn. For this reason, the more pn junctions provided in the nanocolumn, the more sunlight can be converted into electrical energy.

  The present invention relates to a first conductivity type semiconductor substrate having a first surface and a second surface opposite to the first surface, a first electrode provided on the first surface, and a second electrode on the second surface. A nanocolumn region having a plurality of nanocolumns made of InGaN; an InGaN region provided on the nanocolumn region; connected to the plurality of nanocolumns; and a second electrode provided on the InGaN region. Each of the plurality of nanocolumns includes one or a plurality of first conductivity type nanocolumn portions and one or a plurality of second conductivity type nanocolumn portions, and the first conductivity type nanocolumn portion and the second conductivity type nanocolumns. The part is characterized by being provided in order from the semiconductor substrate toward the InGaN region and forming a pn junction.

  The solar cell of the present invention has a nanocolumn made of a gallium nitride compound. This nanocolumn has a lower dislocation density than a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Light is incident on the pn junction of each nanocolumn. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. A plurality of pn junctions are provided in the nanocolumn. For this reason, the more pn junctions provided in the nanocolumn, the more sunlight can be converted into electrical energy.

  The present invention relates to a first conductivity type semiconductor substrate having a first surface and a second surface opposite to the first surface, a first electrode provided on the first surface, and a second electrode on the second surface. A nanocolumn region having a plurality of nanocolumns made of InGaN; an InGaN region provided on the nanocolumn region; connected to the plurality of nanocolumns; and a second electrode provided on the InGaN region. Each of the plurality of nanocolumns extends from the semiconductor substrate toward the InGaN region. The InGaN region includes a first InGaN portion connected to the plurality of nanocolumns and a first InGaN portion provided on the first InGaN portion. The second InGaN portion has a conductivity type different from that of the first InGaN portion, and the first InGaN portion and the second InGaN portion form a first pn junction. That, characterized in that.

  The solar cell of the present invention has a nanocolumn made of a gallium nitride compound. This nanocolumn has a lower dislocation density than a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased.

  According to the present invention, each of the plurality of nanocolumns includes one or more first conductivity type nanocolumn portions and one or more second conductivity type nanocolumn portions, and the first conductivity type nanocolumn portion and the second conductivity type. The nanocolumn portion of the mold is characterized by being provided in order from the semiconductor substrate toward the InGaN region and forming a second pn junction.

  The solar cell of the present invention has a nanocolumn made of a gallium nitride compound. This nanocolumn has a lower dislocation density than a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Light is incident on the pn junction of each nanocolumn. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. A plurality of pn junctions are provided in the nanocolumn. For this reason, the more pn junctions provided in the nanocolumn, the more sunlight can be converted into electrical energy.

  The present invention provides a first electrode, a nanocolumn region having a plurality of nanocolumns made of InGaN, and an InGaN region provided on the nanocolumn region and connected to the plurality of nanocolumns. A second electrode provided on the InGaN region, each of the plurality of nanocolumns includes one or more first conductivity type nanocolumn portions and one or more second conductivity type nanocolumn portions, The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion are sequentially provided from the first electrode toward the InGaN region and form a pn junction.

  The solar cell of the present invention has a nanocolumn made of a gallium nitride compound. This nanocolumn has a lower dislocation density than a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Light is incident on the pn junction of each nanocolumn. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. A plurality of pn junctions are provided in the nanocolumn. For this reason, the more pn junctions provided in the nanocolumn, the more sunlight can be converted into electrical energy.

  The present invention provides a first electrode, a nanocolumn region having a plurality of nanocolumns made of InGaN, and an InGaN region provided on the nanocolumn region and connected to the plurality of nanocolumns. , A second electrode provided on the InGaN region, and each of the plurality of nanocolumns extends from the first electrode toward the InGaN region, and the InGaN region is connected to the plurality of nanocolumns. And a second InGaN portion provided on the first InGaN portion, and the second InGaN portion has a conductivity type different from that of the first InGaN portion, and the first InGaN portion and the second InGaN portion The second InGaN portion forms a first pn junction.

  The solar cell of the present invention has a nanocolumn made of a gallium nitride compound. This nanocolumn has a lower dislocation density than a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased.

  According to the present invention, each of the plurality of nanocolumns includes one or more first conductivity type nanocolumn portions and one or more second conductivity type nanocolumn portions, and the first conductivity type nanocolumn portion and the second conductivity type. The nanocolumn portion of the mold is characterized in that it is provided in order from the first electrode toward the InGaN region and forms a first pn junction.

  The solar cell of the present invention has a nanocolumn made of a gallium nitride compound. This nanocolumn has a lower dislocation density than a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Light is incident on the pn junction of each nanocolumn. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. A plurality of pn junctions are provided in the nanocolumn. For this reason, the more pn junctions provided in the nanocolumn, the more sunlight can be converted into electrical energy.

  ADVANTAGE OF THE INVENTION According to this invention, the solar cell with which the conversion efficiency from optical energy to electrical energy was improved can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the description of the drawings, where possible, the same reference numerals are assigned to the same elements, and duplicate descriptions may be omitted.

<First Embodiment>
With reference to Fig.1 (a), the structure of the solar cell 1a which concerns on 1st Embodiment is demonstrated. The solar cell 1a includes a first electrode 2a and a first conductivity type semiconductor substrate 6a. The semiconductor substrate 6a has a first surface M1a and a second surface M2a on the opposite side of the first surface M1a. The first electrode 2a is provided on the first surface M1a. The material of the first electrode 2a is, for example, Al or AuSb when the semiconductor substrate 6a is n-type silicon, and is, for example, Al when the semiconductor substrate 6a is p-type silicon, and the semiconductor substrate 6a is n-type GaAs. In this case, for example, Ni / AuGe, and in the case where the semiconductor substrate 6a is p-type GaAs, for example, AuZn. The semiconductor substrate 6a is made of silicon or GaAs. The solar cell 1a further includes a second conductivity type semiconductor region 8a provided on the second surface M2a of the semiconductor substrate 6a, and a nanocolumn region 9a provided on the semiconductor region 8a. The semiconductor region 8a is made of silicon when the semiconductor substrate 6a is silicon, and is made of GaAs when the semiconductor substrate 6a is GaAs. The semiconductor substrate 6a and the semiconductor region 8a form a pn junction. The nanocolumn region 9a has a plurality of nanocolumns 10a made of InGaN. The solar cell 1a further includes a second electrode 24a provided on the nanocolumn region 9a. The material of the second electrode 24a is a translucent electrode such as Ni / Au, Pd / Au, or ITO electrode. The second electrode 24a is connected to the plurality of nanocolumns 10a as shown in FIG.

  The nanocolumn 10a extends in a direction from the semiconductor region 8a toward the second electrode 24a. The nanocolumn 10a includes a first conductivity type first nanocolumn portion 12a and a second conductivity type second nanocolumn portion 14a which are sequentially provided from the semiconductor region 8a toward the second electrode 24a. The first nanocolumn portion 12a is provided on the semiconductor region 8a. The second nanocolumn part 14a is provided at the end of the first nanocolumn part 12a. The first nanocolumn part 12a and the second nanocolumn part 14a form a pn junction. The nanocolumn 10a includes one or more first conductivity type nanocolumn parts (including the first nanocolumn part 12a) and one or more second conductivity type nanocolumn parts (including the second nanocolumn part 14a), The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion may be sequentially provided from the semiconductor region 8a toward the second electrode 24a. In this case, the first conductivity type nanocolumn part and the second conductivity type nanocolumn part form a pn junction. Currently, it is possible to provide five pn junctions in the nanocolumn 10a by alternately providing three first-conductivity-type nanocolumn portions and two second-conductivity-type nanocolumn portions. In addition, the band gap of the material (Si) of the semiconductor substrate 6a is different from the band gap of the material (InGaN) of the nanocolumn 10a. Actually, light energy having a relatively long wavelength can be converted into electric energy by the pn junction formed by the semiconductor substrate 6a and the semiconductor region 8a. On the other hand, the nanocolumn 10a can convert light energy having a relatively short wavelength into electric energy. The first conductivity type may be n-type and the second conductivity type may be p-type, the first conductivity type may be p-type and the second conductivity type may be n-type (the second to second below). The same in 11 embodiments).

  Next, with reference to FIG. 3, the manufacturing process of the solar cell 1a according to the first embodiment will be described. In the step shown in FIG. 3A, first, a first conductivity type semiconductor substrate 6a is prepared. Next, in the step shown in FIG. 3B, a second conductivity type semiconductor region 8a is formed on the second surface M1a of the semiconductor substrate 6a. Thereafter, in the step shown in FIG. 3C, a plurality of first nanocolumn portions 12a of the first conductivity type made of InGaN are formed on the semiconductor region 8a. In the step shown in FIG. 3D, a second conductivity type second nanocolumn portion 14a made of InGaN is formed at each end of the plurality of first nanocolumn portions 12a. The first nanocolumn part 12a and the second nanocolumn part 14a constitute a nanocolumn 10a. In the step shown in FIG. 3E, the second electrode 24a is formed on the nanocolumn region 9a including the plurality of nanocolumns 10a, and the first electrode 2a is formed on the second surface M2a of the semiconductor substrate 6a. . A method of forming the second electrode 24a is shown in FIG. As shown in FIG. 4A, the material of the second electrode 24a is supplied onto the nanocolumn region 9a along the vertical axis A1. The material of the second electrode 24a has directivity when supplied onto the nanocolumn region 9a, and solidifies after the supply. Thereby, the plurality of second nanocolumn portions 14a are connected to the second electrode 24a. In this case, as shown in FIG. 4B, the axis A2 of the nanocolumn 10a (axis passing through the first nanocolumn portion 12a and the second nanocolumn portion 14a) is a predetermined angle θ (for example, 2 degrees to 60 degrees is preferable). Since the material of the second electrode 24a has directivity, the material of the second electrode 24a enters between the nanocolumns 10a, and the second electrode 24a is connected to the first nanocolumn portion 12a and the semiconductor region 8a. Can be avoided. And the solar cell 1a is obtained by dicing to the direction shown to code | symbol A3 in a figure.

  As described above, the solar cell 1a has the nanocolumn 10a made of InGaN. The nanocolumn 10a has a dislocation density lower than that of a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Further, light enters the pn junction of each nanocolumn 10a. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. Further, the band gap of the material (for example, Si) of the semiconductor substrate 6a is different from the band gap of the material (InGaN) of the nanocolumn 10a. For this reason, the wavelength of light converted into electrical energy at the pn junction formed by the semiconductor substrate 6a and the semiconductor region 8a is different from the wavelength of light converted into electrical energy at the pn junction of the nanocolumn 10a. Therefore, electrical energy can be extracted from light of different wavelengths. A plurality of pn junctions are provided in the nanocolumn 10a. For this reason, the more pn junctions provided in the nanocolumn 10a, the more sunlight can be converted into electrical energy. Even if the In composition ratio in the nanocolumn 10a is changed, good crystallinity is maintained. For this reason, the In composition ratio in the nanocolumn 10a can be adjusted without impairing the crystallinity.

Second Embodiment
With reference to FIG.1 (b), the structure of the solar cell 1b which concerns on 2nd Embodiment is demonstrated. The solar cell 1b includes a first electrode 2b and a first conductivity type semiconductor substrate 6b. The semiconductor substrate 6b has a first surface M1b and a second surface M2b on the opposite side of the first surface M1b. The first electrode 2b is provided on the first surface M1b. The material of the first electrode 2b is, for example, Al or AuSb when the semiconductor substrate 6b is n-type silicon, and is, for example, Al when the semiconductor substrate 6b is p-type silicon, and the semiconductor substrate 6b is n-type GaAs. In this case, for example, Ni / AuGe, and in the case where the semiconductor substrate 6b is p-type GaAs, for example, AuZn. The semiconductor substrate 6b is made of silicon or GaAs. The solar cell 1b further includes a second conductivity type semiconductor region 8b provided on the second surface M2b of the semiconductor substrate 6b, and a nanocolumn region 9b provided on the semiconductor region 8b. The semiconductor region 8b is made of silicon when the semiconductor substrate 6b is silicon, and is made of GaAs when the semiconductor substrate 6b is GaAs. The semiconductor substrate 6b and the semiconductor region 8b form a pn junction. The nanocolumn region 9b has a plurality of nanocolumns 10b made of InGaN. The solar cell 1b further includes a second conductivity type InGaN region 18b provided on the nanocolumn region 9b. The InGaN region 18b is connected to the plurality of nanocolumns 10b. The solar cell 1b further includes a second electrode 24b provided on the InGaN region 18b. The material of the second electrode 24b is a translucent electrode such as Ni / Au, Pd / Au, or ITO electrode.

  The nanocolumn 10b extends in a direction from the semiconductor region 8b toward the InGaN region 18b. The nanocolumn 10b includes a first conductivity type first nanocolumn portion 12b and a second conductivity type second nanocolumn portion 14b which are sequentially provided from the semiconductor region 8b toward the InGaN region 18b. The first nanocolumn portion 12b is provided on the semiconductor region 8b. The second nanocolumn portion 14b is provided at the end of the first nanocolumn portion 12b. The first nanocolumn part 12b and the second nanocolumn part 14b form a pn junction. The nanocolumn 10b has one or more first conductivity type nanocolumn parts (including the first nanocolumn part 12b) and one or more second conductivity type nanocolumn parts (including the second nanocolumn part 14b), The first conductivity type nanocolumn part and the second conductivity type nanocolumn part may be provided in order from the semiconductor region 8b toward the InGaN region 18b. In this case, the first conductivity type nanocolumn part and the second conductivity type nanocolumn part form a pn junction. Currently, it is possible to provide five pn junctions in the nanocolumn 10b by alternately providing three first-conductivity-type nanocolumn portions and two second-conductivity-type nanocolumn portions. In addition, the band gap of the material (Si) of the semiconductor substrate 6b is different from the band gap of the material (InGaN) of the nanocolumn 10b. Actually, light energy having a relatively long wavelength can be converted into electric energy by the pn junction formed by the semiconductor substrate 6b and the semiconductor region 8b. On the other hand, the nanocolumn 10b can convert light energy having a relatively short wavelength into electric energy.

  Next, the manufacturing process of the solar cell 1b according to the second embodiment will be described. Similar to the process shown in FIG. 3A, first, a first conductivity type semiconductor substrate 6b is prepared. Next, as in the step shown in FIG. 3B, a second conductivity type semiconductor region 8b is formed on the second surface M1b of the semiconductor substrate 6b. After the formation of the semiconductor region 8b, a plurality of first nanocolumn portions 12b of the first conductivity type made of InGaN are formed on the semiconductor region 8b, as in the step shown in FIG. Then, similarly to the step shown in FIG. 3D, the second conductivity type second nanocolumn portion 14b made of InGaN is formed at each end of the plurality of first nanocolumn portions 12b. The first nanocolumn part 12b and the second nanocolumn part 14b form a nanocolumn 10b. After the formation of the nanocolumns 10b, InGaN regions 18b are formed at the ends of the plurality of second nanocolumn portions 14b. For this reason, the plurality of second nanocolumn portions 14b are connected to the InGaN region 18b. After the formation of the InGaN region 18b, the first electrode 2b is formed on the first surface M1b of the semiconductor substrate 6b, and the second electrode 24b is formed on the InGaN region 18b. After the formation of the first electrode 2b and the second electrode 24b, a solar cell 1b is obtained through a dicing process.

  As described above, the solar cell 1b has the nanocolumn 10b made of InGaN. The nanocolumn 10b has a dislocation density lower than that of a bulk gallium nitride semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. In addition, light enters the pn junction of each nanocolumn 10b. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. Moreover, the band gap of the material (for example, Si) of the semiconductor substrate 6b is different from the band gap of the material (InGaN) of the nanocolumn 10b. For this reason, the wavelength of light converted into electrical energy at the pn junction formed by the semiconductor substrate 6b and the semiconductor region 8b is different from the wavelength of light converted into electrical energy at the pn junction of the nanocolumn 10b. Therefore, electrical energy can be extracted from light of different wavelengths. A plurality of pn junctions are provided in the nanocolumn 10b. For this reason, the more pn junctions provided in the nanocolumn 10b, the more sunlight can be converted into electrical energy. Even if the In composition ratio in the nanocolumn 10b or the InGaN region 18b is changed, good crystallinity is maintained. For this reason, the In composition ratio in the nanocolumn 10b and the InGaN region 18b can be adjusted without impairing the crystallinity.

<Third Embodiment>
With reference to FIG.1 (c), the structure of the solar cell 1c which concerns on 3rd Embodiment is demonstrated. The solar cell 1c includes a first electrode 2c and a first conductivity type semiconductor substrate 6c. The semiconductor substrate 6c has a first surface M1c and a second surface M2c on the opposite side of the first surface M1c. The first electrode 2c is provided on the first surface M1c. The material of the first electrode 2c is, for example, Al or AuSb when the semiconductor substrate 6c is n-type silicon, and is, for example, Al when the semiconductor substrate 6c is p-type silicon, and the semiconductor substrate 6c is n-type GaAs. In this case, for example, Ni / AuGe, and in the case where the semiconductor substrate 6c is p-type GaAs, for example, AuZn. The semiconductor substrate 6c is made of silicon or GaAs. The solar cell 1c further includes a second conductivity type semiconductor region 8c provided on the second surface M2c of the semiconductor substrate 6c, and a nanocolumn region 9c provided on the semiconductor region 8c. The semiconductor region 8c is made of silicon when the semiconductor substrate 6c is silicon, and is made of GaAs when the semiconductor substrate 6c is GaAs. The semiconductor substrate 6c and the semiconductor region 8c form a pn junction. The nanocolumn region 9c has a plurality of nanocolumns 10c made of InGaN. The solar cell 1c further includes an InGaN region 18c provided on the nanocolumn region 9c. The InGaN region 18c is connected to the plurality of nanocolumns 10c. The solar cell 1c further includes a second electrode 24c provided on the InGaN region 18c. The material of the second electrode 24c is a translucent electrode such as Ni / Au, Pd / Au, or ITO electrode.

  The nanocolumn 10c extends in a direction from the semiconductor region 8c toward the InGaN region 18c. The nanocolumn 10c shows the first conductivity type. The InGaN region 18c has a first InGaN portion 20c showing the first conductivity type and a second InGaN portion 22c showing the second conductivity type. The first InGaN portion 20c is provided on the nanocolumn region 9c. The first InGaN portion 20c is connected to the plurality of nanocolumns 10c. The second InGaN portion 22c is provided on the first InGaN portion 20c. The first InGaN portion 20c and the second InGaN portion 22c form a pn junction. The band gap of the material (Si) of the semiconductor substrate 6c is different from the band gap of the material (InGaN) of the InGaN region 18c. Actually, light energy having a relatively long wavelength can be converted into electric energy by the pn junction formed by the semiconductor substrate 6c and the semiconductor region 8c. In contrast, the InGaN region 18c can convert light energy having a relatively short wavelength into electrical energy.

  Next, the manufacturing process of the solar cell 1c according to the third embodiment will be described. Similar to the process shown in FIG. 3A, first, a first conductivity type semiconductor substrate 6c is prepared. Next, as in the step shown in FIG. 3B, a second conductivity type semiconductor region 8c is formed on the second surface M1c of the semiconductor substrate 6c. After the formation of the semiconductor region 8c, a plurality of first conductivity type nanocolumns 10c made of InGaN are formed on the semiconductor region 8c. Then, a first conductivity type first InGaN portion 20c made of InGaN is formed at each end of the plurality of nanocolumns 10c, and a second conductivity type second InGaN portion 22c is formed on the first InGaN portion 20c. Form. For this reason, the plurality of second nanocolumn portions 14c are connected to the InGaN region 18c. The first InGaN portion 20c and the second InGaN portion 22c form an InGaN region 18c. After the formation of the InGaN region 18c, the first electrode 2c is formed on the first surface M1c of the semiconductor substrate 6c, and the second electrode 24c is formed on the InGaN region 18c (on the second InGaN portion 22c). After the formation of the first electrode 2c and the second electrode 24c, a solar cell 1c is obtained through a dicing process.

  As described above, the solar cell 1c has the nanocolumn 10c made of InGaN. This nanocolumn 10c has a low dislocation density compared to a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Even if the In composition ratio in the nanocolumn 10c or the InGaN region 18c is changed, good crystallinity is maintained. For this reason, the In composition ratio in the nanocolumn 10c and the InGaN region 18c can be adjusted without impairing the crystallinity.

<Fourth embodiment>
With reference to FIG.1 (d), the structure of the solar cell 1d which concerns on 4th Embodiment is demonstrated. The solar cell 1d includes a first electrode 2d and a first conductivity type semiconductor substrate 6d. The semiconductor substrate 6d has a first surface M1d and a second surface M2d on the opposite side of the first surface M1d. The first electrode 2d is provided on the first surface M1d. The material of the first electrode 2d is, for example, Al or AuSb when the semiconductor substrate 6d is n-type silicon, and is, for example, Al when the semiconductor substrate 6d is p-type silicon, and the semiconductor substrate 6d is n-type GaAs. In this case, for example, Ni / AuGe, and in the case where the semiconductor substrate 6d is p-type GaAs, for example, AuZn. The semiconductor substrate 6d is made of silicon or GaAs. The solar cell 1d further includes a second conductivity type semiconductor region 8d provided on the second surface M2d of the semiconductor substrate 6d, and a nanocolumn region 9d provided on the semiconductor region 8d. The semiconductor region 8d is made of silicon when the semiconductor substrate 6d is silicon, and is made of GaAs when the semiconductor substrate 6d is GaAs. The semiconductor substrate 6d and the semiconductor region 8d form a pn junction. The nanocolumn region 9d has a plurality of nanocolumns 10d made of InGaN. The solar cell 1d further includes an InGaN region 18d provided on the nanocolumn region 9d. The InGaN region 18d is connected to the plurality of nanocolumns 10d. The solar cell 1d further includes a second electrode 24d provided on the InGaN region 18d. The material of the second electrode 24d is a translucent electrode such as Ni / Au, Pd / Au, or ITO electrode.

  The nanocolumn 10d extends in a direction from the semiconductor region 8d toward the InGaN region 18d. The nanocolumn 10d includes a first conductivity type first nanocolumn portion 12d, a second conductivity type second nanocolumn portion 14d, and a third nanocolumn portion 16d that are sequentially provided from the semiconductor region 8d toward the InGaN region 18d. The first nanocolumn portion 12d is provided on the semiconductor region 8d. The second nanocolumn portion 14d is provided at the end of the first nanocolumn portion 12d. The third nanocolumn portion 16d is provided at the end of the second nanocolumn portion 14d. The first nanocolumn part 12d and the second nanocolumn part 14d form a pn junction. The second nanocolumn part 14d and the third nanocolumn part 16d form a pn junction. The nanocolumn 10d includes one or more first conductivity type nanocolumn portions (including the first nanocolumn portion 12d and the third nanocolumn portion 16d) and one or more second conductivity type nanocolumn portions (including the second nanocolumn portion 14d). The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion may be provided in order from the semiconductor region 8d toward the InGaN region 18d. In this case, the first conductivity type nanocolumn part and the second conductivity type nanocolumn part form a pn junction. Currently, it is possible to provide five pn junctions in the nanocolumn 10d by alternately providing three first-conductivity-type nanocolumn portions and two second-conductivity-type nanocolumn portions.

  The InGaN region 18d includes a first InGaN portion 20d that exhibits the first conductivity type, and a second InGaN portion 22d that exhibits the second conductivity type. The first InGaN portion 20d is provided on the nanocolumn region 9d. The first InGaN portion 20d is connected to the plurality of nanocolumns 10d. The second InGaN portion 22d is provided on the first InGaN portion 20d. The first InGaN portion 20d and the second InGaN portion 22d form a pn junction. Further, the band gap of the material (Si) of the semiconductor substrate 6d is different from the band gap of the material (InGaN) of the nanocolumn 10d. Actually, light energy having a relatively long wavelength can be converted into electric energy by the pn junction formed by the semiconductor substrate 6d and the semiconductor region 8d. In contrast, the nanocolumn 10d can convert light energy having a relatively short wavelength into electrical energy.

  Next, the manufacturing process of the solar cell 1d according to the fourth embodiment will be described. Similar to the process shown in FIG. 3A, first, a first conductivity type semiconductor substrate 6d is prepared. Next, similarly to the step shown in FIG. 3B, a second conductivity type semiconductor region 8d is formed on the second surface M1d of the semiconductor substrate 6d. After the formation of the semiconductor region 8d, similarly to the step shown in FIG. 3C, a plurality of first nanocolumn portions 12d of the first conductivity type made of InGaN are formed on the semiconductor region 8d. Similar to the step shown in FIG. 3D, a second nanocolumn portion 14d of the second conductivity type made of InGaN is formed at each end of the plurality of first nanocolumn portions 12d. Then, a first conductivity type third nanocolumn portion 16d made of InGaN is formed at each end of the plurality of second nanocolumn portions 14d. The first nanocolumn part 12d, the second nanocolumn part 14d, and the third nanocolumn part 16d constitute a nanocolumn 10d. After the formation of the nanocolumn 10d, the first InGaN portion 20d of the first conductivity type is formed at the ends of the plurality of second nanocolumn portions 14d, and the second InGaN portion 22d is formed on the first InGaN portion 20d. To do. The first InGaN portion 20d and the second InGaN portion 22d form an InGaN region 18d. After the formation of the InGaN region 18d, the first electrode 2d is formed on the first surface M1d of the semiconductor substrate 6d, and the second electrode 24d is formed on the InGaN region 18d (on the second InGaN portion 22d). After the formation of the first electrode 2d and the second electrode 24d, a solar cell 1d is obtained through a dicing process.

  As described above, the solar cell 1d has the nanocolumn 10d made of InGaN. This nanocolumn 10d has a dislocation density lower than that of a bulk gallium nitride semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Light is incident on the pn junction of each nanocolumn 10d. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. Further, the band gap of the material (for example, Si) of the semiconductor substrate 6d is different from the band gap of the material (InGaN) of the nanocolumn 10d. For this reason, the wavelength of light converted into electrical energy at the pn junction formed by the semiconductor substrate 6d and the semiconductor region 8d is different from the wavelength of light converted into electrical energy at the pn junction of the nanocolumn 10d. Therefore, electrical energy can be extracted from light of different wavelengths. A plurality of pn junctions are provided in the nanocolumn 10d. For this reason, the more pn junctions provided in the nanocolumn 10d, the more sunlight can be converted into electrical energy. Even if the In composition ratio in the nanocolumn 10d or the InGaN region 18d is changed, good crystallinity is maintained. Therefore, the In composition ratio in the nanocolumn 10d and the InGaN region 18d can be adjusted without impairing the crystallinity.

<Fifth Embodiment>
With reference to Fig.5 (a), the structure of the solar cell 1e which concerns on 5th Embodiment is demonstrated. The solar cell 1e includes a first electrode 2e and a first conductivity type semiconductor substrate 6e. The semiconductor substrate 6e has a first surface M1e and a second surface M2e on the opposite side of the first surface M1e. The first electrode 2e is provided on the first surface M1e. The material of the first electrode 2e is, for example, Al or AuSb when the semiconductor substrate 6e is n-type silicon, and is, for example, Al when the semiconductor substrate 6e is p-type silicon, and the semiconductor substrate 6e is n-type GaAs. In this case, for example, Ni / AuGe, and in the case where the semiconductor substrate 6e is p-type GaAs, for example, AuZn. The semiconductor substrate 6e is made of silicon or GaAs. The solar cell 1e further includes a nanocolumn region 9e provided on the second surface M2e of the semiconductor substrate 6e. The nanocolumn region 9e has a plurality of nanocolumns 10e made of InGaN. The solar cell 1e further includes a second electrode 24e provided on the nanocolumn region 9e. The material of the second electrode 24e is a translucent electrode such as Ni / Au, Pd / Au, or ITO electrode. The second electrode 24e is connected to the plurality of nanocolumns 10e. The shape of the second electrode 24e is the same as the shape of the second electrode 24a according to the first embodiment shown in FIG.

  The nanocolumn 10e extends in a direction from the semiconductor substrate 6e toward the second electrode 24e. The nanocolumn 10e includes a first conductivity type first nanocolumn portion 12e and a second conductivity type second nanocolumn portion 14e which are sequentially provided from the semiconductor substrate 6e toward the second electrode 24e. The first nanocolumn portion 12e is provided on the semiconductor region 8e. The second nanocolumn part 14e is provided at the end of the first nanocolumn part 12e. The first nanocolumn part 12e and the second nanocolumn part 14e form a pn junction. The nanocolumn 10e has one or more first conductivity type nanocolumn parts (including the first nanocolumn part 12e) and one or more second conductivity type nanocolumn parts (including the second nanocolumn part 14e), The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion may be sequentially provided from the semiconductor substrate 6e toward the second electrode 24e. In this case, the first conductivity type nanocolumn part and the second conductivity type nanocolumn part form a pn junction. Currently, it is possible to provide five pn junctions in the nanocolumn 10e by alternately providing three first-conductivity-type nanocolumn portions and two second-conductivity-type nanocolumn portions.

  Next, the manufacturing process of the solar cell 1e according to the fifth embodiment will be described. Similar to the process shown in FIG. 3A, first, a first conductivity type semiconductor substrate 6e is prepared. Then, a plurality of first nanocolumn portions 12e of the first conductivity type made of InGaN are formed on the semiconductor substrate 6e. After the formation of the first nanocolumn portion 12e, a second conductivity type second nanocolumn portion 14e made of InGaN is formed at each end of the plurality of first nanocolumn portions 12e. Then, a first conductivity type third nanocolumn portion 16e made of InGaN is formed at each end of the plurality of second nanocolumn portions 14e. The first nanocolumn part 12e, the second nanocolumn part 14e, and the third nanocolumn part 16e constitute a nanocolumn 10e. After the formation of the nanocolumn 10e, in the same manner as the step shown in FIG. 3E and the method of forming the second electrode 24a shown in FIGS. 4A and 4B, the nanocolumn 10e is formed. In addition, the second electrode 24e is formed, and the first electrode 2e is formed on the second surface M2e of the semiconductor substrate 6e. And the solar cell 1e is obtained through a dicing process.

  As described above, the solar cell 1e has the nanocolumn 10e made of InGaN. The nanocolumn 10e has a dislocation density lower than that of a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. In addition, light enters the pn junction of each nanocolumn 10e. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. A plurality of pn junctions are provided in the nanocolumn 10e. For this reason, the more pn junctions provided in the nanocolumn 10e, the more sunlight can be converted into electrical energy. Even if the In composition ratio in the nanocolumn 10e is changed, good crystallinity is maintained. For this reason, the In composition ratio in the nanocolumn 10e can be adjusted without impairing the crystallinity.

<Sixth Embodiment>
With reference to FIG.5 (b), the structure of the solar cell 1f which concerns on 6th Embodiment is demonstrated. The solar cell 1f includes a first electrode 2f and a first conductivity type semiconductor substrate 6f. The semiconductor substrate 6f has a first surface M1f and a second surface M2f on the opposite side of the first surface M1f. The first electrode 2f is provided on the first surface M1f. The material of the first electrode 2f is, for example, Al or AuSb when the semiconductor substrate 6f is n-type silicon, and is, for example, Al when the semiconductor substrate 6f is p-type silicon. The semiconductor substrate 6f is n-type GaAs. In this case, for example, Ni / AuGe, and in the case where the semiconductor substrate 6f is p-type GaAs, for example, AuZn. The semiconductor substrate 6f is made of silicon or GaAs. The solar cell 1f further includes a nanocolumn region 9f provided on the second surface M2f of the semiconductor substrate 6f. The nanocolumn region 9f has a plurality of nanocolumns 10f made of InGaN. The solar cell 1f further includes a second conductivity type InGaN region 18f provided on the nanocolumn region 9f. The InGaN region 18f is connected to the plurality of nanocolumns 10f. The solar cell 1f further includes a second electrode 24f provided on the InGaN region 18f. The material of the second electrode 24f is a translucent electrode such as Ni / Au, Pd / Au, or ITO electrode.

  The nanocolumn 10f extends in a direction from the semiconductor substrate 6f toward the InGaN region 18f. The nanocolumn 10f includes a first conductivity type first nanocolumn portion 12f and a second conductivity type second nanocolumn portion 14f which are sequentially provided from the semiconductor substrate 6f toward the InGaN region 18f. The first nanocolumn portion 12f is provided on the semiconductor region 8f. The second nanocolumn portion 14f is provided at the end of the first nanocolumn portion 12f. The first nanocolumn portion 12f and the second nanocolumn portion 14f form a pn junction. The nanocolumn 10f includes one or more first conductivity type nanocolumn parts (including the first nanocolumn part 12f) and one or more second conductivity type nanocolumn parts (including the second nanocolumn part 14f), The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion may be provided in order from the semiconductor substrate 6f toward the InGaN region 18f. In this case, the first conductivity type nanocolumn part and the second conductivity type nanocolumn part form a pn junction. Currently, five pn junctions can be provided in the nanocolumn 10f by alternately providing three first-conductivity-type nanocolumn portions and two second-conductivity-type nanocolumn portions.

  Next, the manufacturing process of the solar cell 1f according to the sixth embodiment will be described. Similar to the step shown in FIG. 3A, first, a first conductivity type semiconductor substrate 6f is prepared. Next, a plurality of first nanocolumn portions 12f of the first conductivity type made of InGaN are formed on the semiconductor substrate 6f. Then, similarly to the step shown in FIG. 3D, the second conductivity type second nanocolumn portion 14f made of InGaN is formed at each end of the plurality of first nanocolumn portions 12f. The first nanocolumn portion 12f and the second nanocolumn portion 14f form a nanocolumn 10f. After the formation of the nanocolumns 10f, InGaN regions 18f are formed at the ends of the plurality of second nanocolumn portions 14f. For this reason, the plurality of second nanocolumn portions 14f are connected to the InGaN region 18f. After the formation of the InGaN region 18f, the first electrode 2f is formed on the first surface M1f of the semiconductor substrate 6f, and the second electrode 24f is formed on the InGaN region 18f. After the formation of the first electrode 2f and the second electrode 24f, a solar cell 1f is obtained through a dicing process.

  As described above, the solar cell 1f includes the nanocolumn 10f made of InGaN. The nanocolumn 10f has a dislocation density lower than that of a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. In addition, light enters the pn junction of each nanocolumn 10f. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. A plurality of pn junctions are provided in the nanocolumn 10f. For this reason, the more pn junctions provided in the nanocolumn 10f, the more sunlight can be converted into electric energy. Even if the In composition ratio in the nanocolumn 10f or the InGaN region 18f is changed, good crystallinity is maintained. Therefore, the In composition ratio in the nanocolumn 10f and the InGaN region 18f can be adjusted without impairing the crystallinity.

<Seventh embodiment>
With reference to FIG.5 (c), the structure of the solar cell 1g which concerns on 7th Embodiment is demonstrated. The solar cell 1g includes a first electrode 2g and a first conductivity type semiconductor substrate 6g. The semiconductor substrate 6g has a first surface M1g and a second surface M2g on the opposite side of the first surface M1g. The first electrode 2g is provided on the first surface M1g. The material of the first electrode 2g is, for example, Al or AuSb when the semiconductor substrate 6g is n-type silicon, and is, for example, Al when the semiconductor substrate 6g is p-type silicon, and the semiconductor substrate 6g is n-type GaAs. In this case, for example, Ni / AuGe, and in the case where the semiconductor substrate 6g is p-type GaAs, for example, AuZn. The semiconductor substrate 6g is made of silicon or GaAs. The solar cell 1g further includes a nanocolumn region 9g provided on the second surface M2g of the semiconductor substrate 6g. The nanocolumn region 9g has a plurality of nanocolumns 10g made of InGaN. The solar cell 1g further includes an InGaN region 18g provided on the nanocolumn region 9g. The InGaN region 18g is connected to the plurality of nanocolumns 10g. The solar cell 1g further includes a second electrode 24g provided on the InGaN region 18g. The material of the second electrode 24g is a translucent electrode such as Ni / Au, Pd / Au, or ITO electrode.

  The nanocolumn 10g extends in a direction from the semiconductor substrate 6g toward the InGaN region 18g. The nanocolumn 10g indicates the first conductivity type. The InGaN region 18g has a first InGaN portion 20g showing the first conductivity type and a second InGaN portion 22g showing the second conductivity type. The first InGaN portion 20g is provided on the nanocolumn region 9g. The first InGaN portion 20g is connected to the plurality of nanocolumns 10g. The second InGaN portion 22g is provided on the first InGaN portion 20g. The first InGaN portion 20g and the second InGaN portion 22g form a pn junction.

  Next, the manufacturing process of the solar cell 1g according to the seventh embodiment will be described. Similar to the step shown in FIG. 3A, first, a first conductivity type semiconductor substrate 6g is prepared. Next, a plurality of first conductivity type nanocolumns 10g made of InGaN are formed on the semiconductor substrate 6g. A first conductivity type first InGaN portion 20g made of InGaN is formed at each end of the plurality of nanocolumns 10g, and a second conductivity type second InGaN portion 22g is formed on the first InGaN portion 20g. Form. For this reason, the plurality of second nanocolumn portions 14g are connected to the InGaN region 18g. The first InGaN portion 20g and the second InGaN portion 22g form an InGaN region 18g. After the formation of the InGaN region 18g, the first electrode 2g is formed on the first surface M1c of the semiconductor substrate 6g, and the second electrode 24g is formed on the InGaN region 18g (on the second InGaN portion 22g). After the formation of the first electrode 2g and the second electrode 24g, a solar cell 1g is obtained through a dicing process.

  As described above, the solar cell 1g has the nanocolumn 10g made of InGaN. The nanocolumn 10g has a dislocation density lower than that of a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Even if the In composition ratio in the nanocolumn 10g or the InGaN region 18g is changed, good crystallinity is maintained. For this reason, the In composition ratio in the nanocolumn 10g and the InGaN region 18g can be adjusted without impairing the crystallinity.

<Eighth Embodiment>
With reference to FIG.5 (d), the structure of the solar cell 1h which concerns on 8th Embodiment is demonstrated. The solar cell 1h includes a first electrode 2h and a first conductivity type semiconductor substrate 6h. The semiconductor substrate 6h has a first surface M1h and a second surface M2h on the opposite side of the first surface M1h. The first electrode 2h is provided on the first surface M1h. The material of the first electrode 2h is, for example, Al or AuSb when the semiconductor substrate 6h is n-type silicon, and is, for example, Al when the semiconductor substrate 6h is p-type silicon, and the semiconductor substrate 6h is n-type GaAs. In this case, for example, Ni / AuGe, and in the case where the semiconductor substrate 6h is p-type GaAs, for example, AuZn. The semiconductor substrate 6h is made of silicon or GaAs. The solar cell 1h further includes a nanocolumn region 9h provided on the second surface M2h of the semiconductor substrate 6h. The nanocolumn region 9h has a plurality of nanocolumns 10h made of InGaN. The solar cell 1h further includes an InGaN region 18h provided on the nanocolumn region 9h. The InGaN region 18h is connected to the plurality of nanocolumns 10h. The solar cell 1h further includes a second electrode 24h provided on the InGaN region 18h. The material of the second electrode 24h is, for example, a translucent electrode such as Ni / Au, Pd / Au, or ITO electrode.

  The nanocolumn 10h extends in a direction from the semiconductor substrate 6h toward the InGaN region 18h. The nanocolumn 10h includes a first conductivity type first nanocolumn portion 12h, a second conductivity type second nanocolumn portion 14h, and a third nanocolumn portion 16h, which are sequentially provided from the semiconductor substrate 6h toward the InGaN region 18h. The first nanocolumn portion 12h is provided on the semiconductor substrate 6h. The second nanocolumn portion 14h is provided at the end of the first nanocolumn portion 12h. The third nanocolumn portion 16h is provided at the end of the second nanocolumn portion 14h. The first nanocolumn part 12h and the second nanocolumn part 14h form a pn junction. The second nanocolumn part 14h and the third nanocolumn part 16h form a pn junction. The nanocolumn 10h includes one or more first conductivity type nanocolumn parts (including the first nanocolumn part 12h and the third nanocolumn part 16h) and one or more second conductivity type nanocolumn parts (including the second nanocolumn part 14h). The first conductivity type nanocolumn part and the second conductivity type nanocolumn part may be provided in order from the semiconductor substrate 6h toward the InGaN region 18h. In this case, the first conductivity type nanocolumn part and the second conductivity type nanocolumn part form a pn junction. Currently, it is possible to provide five pn junctions in the nanocolumn 10h by alternately providing three first-conductivity-type nanocolumn portions and two second-conductivity-type nanocolumn portions.

  The InGaN region 18h has a first InGaN portion 20h showing the first conductivity type and a second InGaN portion 22h showing the second conductivity type. The first InGaN portion 20h is provided on the nanocolumn region 9h. The first InGaN portion 20h is connected to the plurality of nanocolumns 10h. The second InGaN portion 22h is provided on the first InGaN portion 20h. One pn junction is formed by the first InGaN portion 20h and the second InGaN portion 22h.

  Next, the manufacturing process of the solar cell 1h according to the eighth embodiment will be described. Similar to the process shown in FIG. 3A, first, a first conductivity type semiconductor substrate 6h is prepared. Next, a plurality of first conductivity type first nanocolumn portions 12h made of InGaN are formed on the semiconductor substrate 6h. Similar to the process shown in FIG. 3D, the second conductivity type second nanocolumn portion 14h made of InGaN is formed at each end of the plurality of first nanocolumn portions 12h. Then, a first conductivity type third nanocolumn portion 16h made of InGaN is formed at each end of the plurality of second nanocolumn portions 14h. The first nanocolumn portion 12h, the second nanocolumn portion 14h, and the third nanocolumn portion 16h constitute a nanocolumn 10h. After the formation of the nanocolumns 10h, the first conductivity type first InGaN portions 20h are formed at the ends of the plurality of second nanocolumn portions 14h, and the second InGaN portions 22h are formed on the first InGaN portions 20h. To do. The first InGaN portion 20h and the second InGaN portion 22h form an InGaN region 18h. After the formation of the InGaN region 18h, the first electrode 2h is formed on the first surface M1h of the semiconductor substrate 6h, and the second electrode 24h is formed on the InGaN region 18h (on the second InGaN portion 22h). After the formation of the first electrode 2h and the second electrode 24h, a solar cell 1h is obtained through a dicing process.

  As described above, the solar cell 1h has the nanocolumn 10h made of InGaN. The nanocolumn 10h has a dislocation density lower than that of a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Further, light enters the pn junction of each nanocolumn 10h. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. A plurality of pn junctions are provided in the nanocolumn 10f. For this reason, the more pn junctions provided in the nanocolumn 10f, the more sunlight can be converted into electric energy. Even if the In composition ratio in the nanocolumn 10h or the InGaN region 18h is changed, good crystallinity is maintained. For this reason, the In composition ratio in the nanocolumn 10h and the InGaN region 18h can be adjusted without impairing the crystallinity.

<Ninth Embodiment>
With reference to Fig.6 (a), the structure of the solar cell 1i which concerns on 9th Embodiment is demonstrated. The solar cell 1i includes a first electrode 2i and a nanocolumn region 9i provided on the first electrode 2i. The material of the first electrode 2i is, for example, Ti / Al. The shape of the first electrode 2i is the same as the shape of the second electrode 24a according to the first embodiment shown in FIG. The nanocolumn region 9i has a plurality of nanocolumns 10i made of InGaN. The solar cell 1i further includes a second conductivity type InGaN region 18i provided on the nanocolumn region 9i. The InGaN region 18i is connected to the plurality of nanocolumns 10i. The solar cell 1i further includes a second electrode 24i provided on the InGaN region 18i. The material of the second electrode 24i is a translucent electrode such as Ni / Au, Pd / Au, or ITO electrode.

  The nanocolumn 10i extends in a direction from the first electrode 2i toward the InGaN region 18i. The nanocolumn 10i includes a first conductivity type first nanocolumn portion 12i and a second conductivity type second nanocolumn portion 14i which are sequentially provided from the first electrode 2i toward the InGaN region 18i. The first nanocolumn part 12i is provided on the first electrode 2i. The second nanocolumn part 14i is provided at the end of the first nanocolumn part 12i. The first nanocolumn part 12i and the second nanocolumn part 14i form a pn junction. The nanocolumn 10i has one or a plurality of first conductivity type nanocolumn parts (including the first nanocolumn part 12i) and one or a plurality of second conductivity type nanocolumn parts (including the second nanocolumn part 14i), The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion may be provided in order from the first electrode 2i toward the InGaN region 18i. In this case, the first conductivity type nanocolumn part and the second conductivity type nanocolumn part form a pn junction. Currently, five pn junctions can be provided in the nanocolumn 10i by alternately providing three first-conductivity-type nanocolumn portions and two second-conductivity-type nanocolumn portions.

  In the solar cell 1i, when sunlight is incident from the first electrode 2i, the composition ratio of In contained in the nanocolumn 10i and the InGaN region 18i is smaller as it is closer to the first electrode 2i. Conversely, when sunlight is incident from the second electrode 24i side, the composition ratio of In contained in the nanocolumn 10i and the InGaN region 18i increases as the distance from the first electrode 2i increases.

  Next, the manufacturing process of the solar cell 1i according to the ninth embodiment will be described. Similar to the process shown in FIG. 3A, first, a first conductivity type semiconductor substrate 6i is prepared. Next, a plurality of first nanocolumn portions 12i of the first conductivity type made of InGaN are formed on the semiconductor substrate 6i. Then, similarly to the step shown in FIG. 3D, a second conductivity type second nanocolumn portion 14i made of InGaN is formed at each end of the plurality of first nanocolumn portions 12i. After the formation of the nanocolumns 10i, InGaN regions 18i are formed at the ends of the plurality of second nanocolumn portions 14i. For this reason, the plurality of second nanocolumn portions 14i are connected to the InGaN region 18i. The first nanocolumn part 12i and the second nanocolumn part 14i constitute a nanocolumn 10i. After the formation of the InGaN region 18i, the semiconductor substrate 6i is separated from the first nanocolumn part 12i. Thereafter, the first electrode 2i is formed at the end of the first nanocolumn part 12i in the same manner as the method for forming the first electrode 2a shown in FIGS. 4 (a) and 4 (b). After the formation of the first electrode 2i (or before the formation of the first electrode 2i), the second electrode 24i is formed on the InGaN region 18i. After the formation of the first electrode 2i and the second electrode 24i, a solar cell 1i is obtained through a dicing process.

  As described above, the solar cell 1i has the nanocolumn 10i made of InGaN. This nanocolumn 10i has a dislocation density lower than that of a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. In addition, light enters the pn junction of each nanocolumn 10i. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. A plurality of pn junctions are provided in the nanocolumn 10i. For this reason, the more pn junctions provided in the nanocolumn 10i, the more sunlight can be converted into electrical energy. Even if the In composition ratio in the nanocolumn 10i or the InGaN region 18i is changed, good crystallinity is maintained. For this reason, the In composition ratio in the nanocolumn 10i and the InGaN region 18i can be adjusted without impairing the crystallinity.

<Tenth Embodiment>
With reference to FIG.7 (b), the structure of the solar cell 1j which concerns on 10th Embodiment is demonstrated. The solar cell 1j includes a first electrode 2j and a nanocolumn region 9j provided on the first electrode 2j. The material of the first electrode 2j is, for example, Ti / Al. The shape of the first electrode 2j is the same as the shape of the second electrode 24a according to the first embodiment shown in FIG. The nanocolumn region 9j has a plurality of nanocolumns 10j made of InGaN. The solar cell 1j further includes an InGaN region 18j provided on the nanocolumn region 9j. The InGaN region 18j is connected to the plurality of nanocolumns 10j. The solar cell 1j further includes a second electrode 24j provided on the InGaN region 18j. The material of the second electrode 24j is a translucent electrode such as Ni / Au, Pd / Au, or ITO electrode.

  The nanocolumn 10j extends in the direction from the first electrode 2j toward the InGaN region 18j. The nanocolumn 10j indicates the first conductivity type. The InGaN region 18j has a first InGaN portion 20j showing the first conductivity type and a second InGaN portion 22j showing the second conductivity type. The first InGaN portion 20j is provided on the nanocolumn region 9j. The first InGaN portion 20j is connected to the plurality of nanocolumns 10j. The second InGaN portion 22j is provided on the first InGaN portion 20j. The first InGaN portion 20j and the second InGaN portion 22j form a pn junction.

  In the solar cell 1j, when sunlight is incident from the first electrode 2j, the composition ratio of In contained in the nanocolumn 10j and the InGaN region 18j is smaller as it is closer to the first electrode 2j. Conversely, when sunlight is incident from the second electrode 24j side, the composition ratio of In contained in the nanocolumn 10j and the InGaN region 18j is larger as it is closer to the first electrode 2j.

  Next, the manufacturing process of the solar cell 1j according to the tenth embodiment will be described. Similar to the process shown in FIG. 3A, first, a first conductivity type semiconductor substrate 6j is prepared. Next, as in the step shown in FIG. 3B, a second conductivity type semiconductor region 8j is formed on the second surface M1j of the semiconductor substrate 6j. After the formation of the semiconductor region 8j, a plurality of first conductivity type nanocolumns 10j made of InGaN are formed on the semiconductor region 8j. A first conductivity type first InGaN portion 20j made of InGaN is formed at each end of the plurality of nanocolumns 10j, and a second conductivity type second InGaN portion 22j is formed on the first InGaN portion 20j. Form. For this reason, the plurality of second nanocolumn portions 14j are connected to the InGaN region 18j. The first InGaN portion 20j and the second InGaN portion 22j form an InGaN region 18j. After the formation of the InGaN region 18j, the semiconductor substrate 6j is separated from the first nanocolumn portion 12j. Thereafter, the first electrode 2j is formed at the end of the first nanocolumn portion 12j in the same manner as the method for forming the first electrode 2a shown in FIGS. 4 (a) and 4 (b). After the formation of the first electrode 2j (or before the formation of the first electrode 2j), the second electrode 24j is formed on the second InGaN portion 22j. After the formation of the first electrode 2j and the second electrode 24j, a solar cell 1j is obtained through a dicing process.

  As described above, the solar cell 1j has the nanocolumn 10j made of InGaN. The nanocolumn 10j has a lower dislocation density than the bulk gallium nitride semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Even if the In composition ratio in the nanocolumn 10j or the InGaN region 18j is changed, good crystallinity is maintained. For this reason, the In composition ratio in the nanocolumn 10j and the InGaN region 18j can be adjusted without impairing the crystallinity.

<Eleventh embodiment>
With reference to FIG.7 (c), the structure of the solar cell 1k which concerns on 11th Embodiment is demonstrated. The solar cell 1k includes a first electrode 2k and a nanocolumn region 9k provided on the first electrode 2k. The material of the first electrode 2k is, for example, Ti / Al. The shape of the first electrode 2k is the same as the shape of the second electrode 24a according to the first embodiment shown in FIG. The nanocolumn region 9k has a plurality of nanocolumns 10k made of InGaN. The solar cell 1k further includes an InGaN region 18k provided on the nanocolumn region 9k. The InGaN region 18k is connected to the plurality of nanocolumns 10k. The solar cell 1k further includes a second electrode 24k provided on the InGaN region 18k. The material of the second electrode 24k is a translucent electrode such as Ni / Au, Pd / Au, or ITO electrode.

  The nanocolumn 10k extends in a direction from the first electrode 2k toward the InGaN region 18k. The nanocolumn 10k includes a first conductivity type first nanocolumn portion 12k, a second conductivity type second nanocolumn portion 14k, and a third nanocolumn portion 16k which are sequentially provided from the first electrode 2k toward the InGaN region 18k. The first nanocolumn portion 12k is provided on the first electrode 2k. The second nanocolumn portion 14k is provided at the end of the first nanocolumn portion 12k. The third nanocolumn portion 16k is provided at the end of the second nanocolumn portion 14k. The first nanocolumn part 12k and the second nanocolumn part 14k form a pn junction. The second nanocolumn part 14k and the third nanocolumn part 16k form a pn junction. The nanocolumn 10k includes one or more first conductivity type nanocolumn parts (including the first nanocolumn part 12k and the third nanocolumn part 16k) and one or more second conductivity type nanocolumn parts (including the second nanocolumn part 14k). The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion may be sequentially provided from the first electrode 2k toward the InGaN region 18k. In this case, the first conductivity type nanocolumn part and the second conductivity type nanocolumn part form a pn junction. Currently, it is possible to provide five pn junctions in the nanocolumn 10k by alternately providing three first-conductivity-type nanocolumn portions and two second-conductivity-type nanocolumn portions.

  The InGaN region 18k includes a first InGaN portion 20k that exhibits the first conductivity type, and a second InGaN portion 22k that exhibits the second conductivity type. The first InGaN portion 20k is provided on the nanocolumn region 9k. The first InGaN portion 20k is connected to the plurality of nanocolumns 10k. The second InGaN portion 22k is provided on the first InGaN portion 20k. The first InGaN portion 20k and the second InGaN portion 22k form a pn junction.

  In the solar cell 1k, when sunlight is incident from the first electrode 2k, the composition ratio of In contained in the nanocolumn 10k and the InGaN region 18k is smaller as it is closer to the first electrode 2k. Conversely, when sunlight is incident from the second electrode 24k side, the composition ratio of In contained in the nanocolumn 10k and the InGaN region 18k is larger as it is closer to the first electrode 2k.

  Next, the manufacturing process of the solar cell 1k according to the eleventh embodiment will be described. Similar to the process shown in FIG. 3A, first, a first conductivity type semiconductor substrate 6k is prepared. Next, a plurality of first nanocolumn portions 12k of the first conductivity type made of InGaN are formed on the semiconductor substrate 6k. Similar to the step shown in FIG. 3D, the second conductivity type second nanocolumn portion 14k made of InGaN is formed at each end of the plurality of first nanocolumn portions 12k. Then, a first conductivity type third nanocolumn portion 16k made of InGaN is formed at each end of the plurality of second nanocolumn portions 14k. The first nanocolumn part 12k, the second nanocolumn part 14k, and the third nanocolumn part 16k constitute a nanocolumn 10k. After the formation of the nanocolumn 10k, the first conductivity type first InGaN portion 20k is formed at the end of the plurality of second nanocolumn portions 14k, and the second InGaN portion 22k is formed on the first InGaN portion 20k. To do. The first InGaN portion 20k and the second InGaN portion 22k form an InGaN region 18k. After the formation of the InGaN region 18k, the semiconductor substrate 6k is separated from the first nanocolumn portion 12k. Thereafter, the first electrode 2k is formed at the end of the first nanocolumn portion 12k in the same manner as the method for forming the first electrode 2a shown in FIGS. 4A and 4B. After the formation of the first electrode 2k (or before the formation of the first electrode 2k), the second electrode 24k is formed on the InGaN region 18k. After the formation of the first electrode 2k and the second electrode 24k, a solar cell 1k is obtained through a dicing process.

  As described above, the solar cell 1k includes the nanocolumn 10k made of InGaN. The nanocolumn 10k has a dislocation density lower than that of a bulk gallium nitride based semiconductor region. For this reason, the crystal quality of the semiconductor is improved, and the conversion efficiency from light energy to electrical energy is increased. Light is incident on the pn junction of each nanocolumn 10k. Thereby, more light can be received compared with the case where a pn junction is provided in a bulk semiconductor region. A plurality of pn junctions are provided in the nanocolumn 10k. For this reason, the more pn junctions provided in the nanocolumn 10k, the more sunlight can be converted into electrical energy. Even if the In composition ratio in the nanocolumn 10k or the InGaN region 18k is changed, good crystallinity is maintained. For this reason, the In composition ratio in the nanocolumn 10k and the InGaN region 18k can be adjusted without impairing the crystallinity.

It is sectional drawing for demonstrating the internal structure of the solar cell which concerns on embodiment. It is a figure for demonstrating the structure of the electrode provided on a nano column. It is a figure for demonstrating the manufacturing process of the solar cell which concerns on embodiment. It is a figure for demonstrating the formation method of the electrode on a nanocolumn. It is sectional drawing for demonstrating the internal structure of the solar cell which concerns on embodiment. It is sectional drawing for demonstrating the internal structure of the solar cell which concerns on embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a-1k ... Solar cell, 2a-2k ... 1st electrode, 6a-6k ... Semiconductor substrate, 8a-8d ... Semiconductor region, 9a-9k ... Nanocolumn region, 10a-10k ... Nanocolumn, 12a, 12b, 12d-12g, 12i, 12k ... 1st nano column part, 14a, 14b, 14d-14f, 14h, 14i, 14k ... 2nd nano column part, 16d, 16h, 16k ... 3rd nano column part, 18b-18d, 18f-18k ... InGaN area | region, 20c, 20d, 20g, 20h, 20j, 20k ... first InGaN part, 21a-21k ... first electrode, 22c, 22d, 22g, 22h, 22j, 22k ... second InGaN part, 24a-24k ... second electrode.

Claims (11)

A first conductivity type semiconductor substrate having a first surface and a second surface opposite the first surface;
A first electrode provided on the first surface;
A second conductivity type semiconductor region provided on the second surface;
A nanocolumn region provided on the semiconductor region and having a plurality of nanocolumns made of InGaN;
An InGaN region provided on the nanocolumn region and connected to the plurality of nanocolumns;
A second electrode provided on the InGaN region,
The semiconductor substrate and the semiconductor region form a first pn junction;
Each of the plurality of nanocolumns includes one or more first conductivity type nanocolumn parts and one or more second conductivity type nanocolumn parts,
The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion are sequentially provided from the semiconductor region toward the InGaN region and form a second pn junction,
The InGaN region has a first InGaN portion connected to the plurality of nanocolumns, and a second InGaN portion provided on the first InGaN portion,
The second InGaN portion has a different conductivity type from the first InGaN portion;
The first InGaN portion and the second InGaN portion form a third pn junction,
The solar cell according to claim 1, wherein a band gap of the semiconductor substrate material is different from a band gap of the nanocolumn material. A first conductivity type semiconductor substrate having a first surface and a second surface opposite the first surface;
A first electrode provided on the first surface;
A second conductivity type semiconductor region provided on the second surface;
A nanocolumn region provided on the semiconductor region and having a plurality of nanocolumns made of InGaN;
A second electrode provided on the nanocolumn region and connected to the plurality of nanocolumns;
The semiconductor substrate and the semiconductor region form a first pn junction;
Each of the plurality of nanocolumns includes one or more first conductivity type nanocolumn parts and one or more second conductivity type nanocolumn parts,
The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion are sequentially provided from the semiconductor region toward the second electrode and form a second pn junction,
The solar cell according to claim 1, wherein a band gap of the semiconductor substrate material is different from a band gap of the nanocolumn material. A first conductivity type semiconductor substrate having a first surface and a second surface opposite the first surface;
A first electrode provided on the first surface;
A second conductivity type semiconductor region provided on the second surface;
A nanocolumn region provided on the semiconductor region and having a plurality of nanocolumns made of InGaN;
An InGaN region provided on the nanocolumn region and connected to the plurality of nanocolumns;
A second electrode provided on the InGaN region,
The semiconductor substrate and the semiconductor region form a first pn junction;
Each of the plurality of nanocolumns includes one or more first conductivity type nanocolumn parts and one or more second conductivity type nanocolumn parts,
The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion are sequentially provided from the semiconductor region toward the InGaN region and form a second pn junction,
The solar cell according to claim 1, wherein a band gap of the semiconductor substrate material is different from a band gap of the nanocolumn material. A first conductivity type semiconductor substrate having a first surface and a second surface opposite the first surface;
A first electrode provided on the first surface;
A second conductivity type semiconductor region provided on the second surface;
A nanocolumn region provided on the semiconductor region and having a plurality of nanocolumns made of InGaN;
An InGaN region provided on the nanocolumn region and connected to the plurality of nanocolumns;
A second electrode provided on the InGaN region,
The semiconductor substrate and the semiconductor region form a first pn junction;
Each of the plurality of nanocolumns extends from the semiconductor region toward the InGaN region,
The InGaN region has a first InGaN portion connected to the plurality of nanocolumns, and a second InGaN portion provided on the first InGaN portion,
The second InGaN portion has a different conductivity type from the first InGaN portion;
The first InGaN portion and the second InGaN portion form a second pn junction,
The solar cell according to claim 1, wherein a band gap of the material of the semiconductor substrate is different from a band gap of the material of the InGaN region. A first conductivity type semiconductor substrate having a first surface and a second surface opposite the first surface;
A first electrode provided on the first surface;
A nanocolumn region provided on the second surface and having a plurality of nanocolumns made of InGaN;
A second electrode provided on the nanocolumn region and connected to the plurality of nanocolumns;
Each of the plurality of nanocolumns includes one or more first conductivity type nanocolumn parts and one or more second conductivity type nanocolumn parts,
The first conductivity type nanocolumn part and the second conductivity type nanocolumn part are sequentially provided from the semiconductor substrate toward the second electrode and form a pn junction. . A first conductivity type semiconductor substrate having a first surface and a second surface opposite the first surface;
A first electrode provided on the first surface;
A nanocolumn region provided on the second surface and having a plurality of nanocolumns made of InGaN;
An InGaN region provided on the nanocolumn region and connected to the plurality of nanocolumns;
A second electrode provided on the InGaN region,
Each of the plurality of nanocolumns includes one or more first conductivity type nanocolumn parts and one or more second conductivity type nanocolumn parts,
The first conductivity type nanocolumn part and the second conductivity type nanocolumn part are sequentially provided from the semiconductor substrate toward the InGaN region and form a pn junction. A first conductivity type semiconductor substrate having a first surface and a second surface opposite the first surface;
A first electrode provided on the first surface;
A nanocolumn region provided on the second surface and having a plurality of nanocolumns made of InGaN;
An InGaN region provided on the nanocolumn region and connected to the plurality of nanocolumns;
A second electrode provided on the InGaN region,
Each of the plurality of nanocolumns extends from the semiconductor substrate toward the InGaN region,
The InGaN region has a first InGaN portion connected to the plurality of nanocolumns, and a second InGaN portion provided on the first InGaN portion,
The second InGaN portion has a different conductivity type from the first InGaN portion;
The solar cell according to claim 1, wherein the first InGaN portion and the second InGaN portion form a first pn junction. Each of the plurality of nanocolumns has one or more first conductivity type nanocolumn parts and one or more second conductivity type nanocolumn parts,
The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion are sequentially provided from the semiconductor substrate toward the InGaN region and form a second pn junction. The solar cell according to claim 7. A first electrode;
A nanocolumn region provided on the first electrode and having a plurality of nanocolumns made of InGaN;
An InGaN region provided on the nanocolumn region and connected to the plurality of nanocolumns;
A second electrode provided on the InGaN region,
Each of the plurality of nanocolumns includes one or more first conductivity type nanocolumn parts and one or more second conductivity type nanocolumn parts,
The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion are sequentially provided from the first electrode toward the InGaN region and form a pn junction. . A first electrode;
A nanocolumn region provided on the first electrode and having a plurality of nanocolumns made of InGaN;
An InGaN region provided on the nanocolumn region and connected to the plurality of nanocolumns;
A second electrode provided on the InGaN region,
Each of the plurality of nanocolumns extends from the first electrode toward the InGaN region,
The InGaN region has a first InGaN portion connected to the plurality of nanocolumns, and a second InGaN portion provided on the first InGaN portion,
The second InGaN portion has a different conductivity type from the first InGaN portion;
The solar cell according to claim 1, wherein the first InGaN portion and the second InGaN portion form a first pn junction. Each of the plurality of nanocolumns has one or more first conductivity type nanocolumn parts and one or more second conductivity type nanocolumn parts,
The first conductivity type nanocolumn portion and the second conductivity type nanocolumn portion are sequentially provided from the first electrode toward the InGaN region and form a second pn junction. The solar cell according to claim 10.

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