Mitsubishi Denki Kabushiki Kaisha

Hajime Sasaki

Hiroaki Morikawa

Hideo Naomoto

Satoshi Arimoto

Yoshinori Matsuno

Mikio Deguchi

Kazuhiko Satoh

Takashi Ishihara

Masao Aiga

A method for producing a thin film solar cell includes preparing a substrate of a low purity material and having opposed front and rear surfaces; forming an insulating film on the front surface of the substrate; forming a second conductivity type active layer of a high purity material on the insulating film with a front surface exposed; forming a second conductivity type semiconductor region within the active layer, reaching the front surface, to produce a p-n junction for light-to-electricity conversion; forming an anti-reflection film on the front surface of the active layer, the anti-reflection film reducing reflection of incident light; forming a surface electrode in contact with the front surface of the active layer; adhering the front surface side of the active layer to a supporting plate and selectively etching the low purity substrate from the rear surface to form a supporting substrate supporting the active layer; and forming a rear electrode on the rear surface of the supporting substrate contacting the active layer.

Method of producing thin film solar cell

A method of fabricating a microwave semiconductor integrated circuit includes fabricating an integrated circuit including an FET and a wiring surrounding the FET on the front surface of the substrate; forming an insulating film covering a first region of the substrate where the FET is fabricated and a second region of the substrate where the wiring is fabricated; forming a thin resist film on the insulating film covering the first region of the substrate; removing a portion of the insulating film from the second region of the substrate opposite the wiring; forming a metal film containing a gas, covering the thin resist film and contacting, at a peripheral portion, the wiring exposed by removal of the insulating film; forming a hole in from the rear surface of the substrate to reach the thin resist film; forming a space between the metal film and the insulating film by dissolving the thin resist film with a solvent applied through the hole; closing the opening of the hole at the rear surface of the substrate; heating the metal film to make the metal film discharge the gas, thereby expanding the metal film to such an extent that a space produced between the metal film and the gate electrode of the FET does not cause parasitic capacitance between the metal film and the gate electrode.

Method for fabricating microwave semiconductor integrated circuit

A method for producing a thin-film solar cell includes successively depositing a lower anti-reflection film having a relatively large etching rate in a prescribed etchant and an upper anti-reflection film having a relatively small etching rate in the prescribed etchant on a photosensitive surface of a semiconductor substrate; patterning the upper anti-reflection film to form an aperture; and etching the lower anti-reflection film using the patterned upper anti-reflection film as a mask.

Method of producing solar cell

A method for producing a thin-film solar cell having a thin-film active layer on a graphite sheet substrate includes the steps of adhering two sheets of graphite together, forming semiconductor thin films serving as active layers on second main surfaces of the two sheets of graphite, and separating the two sheets of graphite from each other. In this structure, stress caused by a difference in expansion coefficients between the upper sheet and the semiconductor thin film is cancelled by stress caused by a difference in expansion coefficients between the lower sheet and the semiconductor thin film. Therefore, curvature of the substrates is prevented whereby subsequent process steps are easily carried out. In addition, the number of products per unit time is doubled, thereby increasing productivity.

Thin film solar cell and production method therefor

A thin-film solar cell includes a thin active layer of high purity material having opposed front and rear surfaces for light-to-electricity conversion, a structure for supporting the thin active layer, and a rear electrode in contact with the rear surface of the active layer. The supporting structure includes a supporting substrate of a low purity material having opposed front and rear surfaces, on the front surface of which the rear surface of the active layer is disposed, and an insulating barrier layer interposed between the front surface of the supporting substrate and the rear surface of the active layer. The barrier layer prevents impurities in the supporting substrate from diffusing into the active layer. Since the supporting substrate comprises a low purity material, the quantity of the expensive high purity material can be reduced by reducing the thickness of the active layer, resulting in low production costs. Since the supporting substrate is present on the rear surface of the active layer, a surface electrode disposed on the front surface of the active layer is exposed. Therefore, when a solar cell module is fabricated using a plurality of the solar cells, a wire bonding process for connecting adjacent solar cells is easily carried out.

Thin-film solar cell

A thin-film solar cell includes a thin-film active layer with a p-n Junction and a heat-resistant substrate for mechanically supporting the active layer, which substrate is formed by a plasma coating method. In the plasma coating method, a source material of the substrate is melted with a high-temperature plasma and sprayed onto a base plate by a high-speed gas jet. Since the substrate formed by the plasma coating method is porous, even if an inexpensive material including a lot of impurities is used as a material of the substrate, the impurities are collected in pores of the substrate and never sprout out of the substrate breaking through the thin-film active layer.

Thin-film solar cell production method

A method for producing a thin-film solar cell having a thin-film active layer on a graphite sheet substrate includes the steps of adhering two sheets of graphite together, forming semi-conductor thin films serving as active layers on second main surfaces of the two sheets of graphite, and separating the two sheets of graphite from each other. In this structure, stress caused by a difference in expansion coefficients between the upper sheet and the semiconductor thin film is cancelled by stress caused by a difference in expansion coefficients between the lower sheet and the semiconductor thin film. Therefore, curvature of the substrates is prevented whereby subsequent process steps are easily carried out. In addition, the number of products per unit time is doubled, thereby increasing productivity.

Method of producing a thin-film solar cell

A multiple cell photovoltaic device includes first and second serially connected solar cells and a conductive or dielectric selective reflection film therebetween. The thickness of the selective reflection film is chosen to reflect short wavelength light which may be absorbed by the second solar cell and to transmit long wavelength light which is not absorbed by the second solar cell and may be absorbed by the first solar cell. When the selective reflection film comprises a dielectric material, apertures are provided in the selective reflection film for serial electrical connection of the two cells.

Growing community of inventors

Itami, Japan

Hajime Sasaki