Abstract: A system is described for fabricating photovoltaic structures. The system can include a photovoltaic cell enclosure that communicatively couples a first processing station and a second processing station while providing a microenvironment for a plurality of photovoltaic cells. The microenvironment can be separated from a surrounding environment. Furthermore, a microenvironment controller can control density of at least one chemical that could contaminate or react with an oxide layer on a respective photovoltaic cell, thereby protecting the photovoltaic cell between processes.

Abstract: One embodiment of the present invention provides a solar cell. The solar cell includes a substrate, a first heavily doped crystalline-Si (c-Si) layer situated above the substrate, a lightly doped c-Si layer situated above the first heavily doped crystalline-Si layer, a second heavily doped c-Si layer situated above the lightly doped c-Si layer, a front side electrode grid situated above the second heavily doped c-Si layer, and a backside electrode grid situated on the backside of the substrate.

Abstract: One embodiment provides a reactor for material deposition. The reactor includes a chamber and at least one gas nozzle. The chamber includes a pair of susceptors, each having a front side and a back side. The front side mounts a number of substrates. The susceptors are positioned vertically so that the front sides of the susceptors face each other, and the vertical edges of the susceptors are in contact with each other, thereby forming a substantially enclosed narrow channel between the substrates mounted on different susceptors. The gas nozzle includes a gas-inlet component situated in the center and a detachable gas-outlet component stacked around the gas-inlet component. The gas-inlet component includes at least one opening coupled to the chamber, and is configured to inject precursor gases into the chamber. The detachable gas-outlet component includes at least one opening coupled to the chamber, and is configured to output exhaust gases from the chamber.

Abstract: One embodiment of the present invention provides a heterojunction solar cell. The solar cell includes a metallurgical-grade Si (MG-Si) substrate, a layer of heavily doped crystalline-Si situated above the MG-Si substrate, a layer of lightly doped crystalline-Si situated above the heavily doped crystalline-Si layer, a backside ohmic-contact layer situated on the backside of the MG-Si substrate, a passivation layer situated above the heavily doped crystalline-Si layer, a layer of heavily doped amorphous Si (a-Si) situated above the passivation layer, a layer of transparent-conducting-oxide (TCO) situated above the heavily doped a-Si layer, and a front ohmic-contact electrode situated above the TCO layer.

Abstract: One embodiment provides an apparatus for material deposition. The apparatus includes a reaction chamber, and a pair of susceptors. Each susceptor has a front side mounting substrates and a back side. The front sides of the vertically positioned susceptors face each other, and the vertical edges of the susceptors are in contact with each other. The apparatus also includes a number of gas nozzles for injecting reaction gases. The gas flow directions inside the chamber can be alternated by controlling the gas nozzles. The gas nozzles are configured to inject a small amount of purge gas including at least one of: HCl, SiCl4, and H2 when the gas nozzles are not injecting reaction gas. The apparatus includes a number of heating units situated outside the reaction chamber. The heating units are arranged in such a way that they radiate heat energy directly to the back sides of the susceptors.

Abstract: One embodiment of the present invention provides a back junction solar cell. The solar cell includes a base layer, a quantum-tunneling-barrier (QTB) layer situated below the base layer facing away from incident light, an emitter layer situated below the QTB layer, a front surface field (FSF) layer situated above the base layer, a front-side electrode situated above the FSF layer, and a back-side electrode situated below the emitter layer.

Abstract: One embodiment of the present invention provides a solar cell. The solar cell includes a base layer comprising crystalline Si (c-Si), an electron collector situated on a first side of the base layer, and a hole collector situated on a second side of the base layer, which is opposite the first side. The electron collector includes a quantum-tunneling-barrier (QTB) layer situated adjacent to the base layer and a transparent conducting oxide (TCO) layer situated adjacent to the QTB layer. The TCO layer has a work function of less than 4.2 eV.

Abstract: One embodiment of the present invention provides a solar cell. The solar cell includes a photovoltaic structure and a front-side metal grid situated above the photovoltaic structure. The front-side metal grid also includes one or more electroplated metal layers. The front-side metal grid includes one or more finger lines, and each end of a respective finger line is coupled to a corresponding end of an adjacent finger line via an additional metal line, thus ensuring that the respective finger line has no open end.

Abstract: One embodiment of the present invention provides a solar cell. The solar cell includes a base layer comprising crystalline Si (c-Si), a hole collector situated on a first side of the base layer, and an electron collector situated on a second side of the base layer, which is opposite the first side. The hole collector includes a quantum-tunneling-barrier (QTB) layer situated adjacent to the base layer and a transparent conducting oxide (TCO) layer situated adjacent to the QTB layer. The TCO layer has a work function of at least 5.0 eV.

Abstract: One embodiment of the present invention provides a tunneling junction based solar cell. The solar cell includes a base layer; a quantum-tunneling-barrier (QTB) layer situated adjacent to the base layer; an emitter; a surface field layer; a front-side electrode; and a back-side electrode.

Abstract: One embodiment provides an apparatus for material deposition. The apparatus includes a reaction chamber, and a pair of susceptors. Each susceptor has a front side and a back side, and the front side mounts substrates. The susceptors are positioned vertically in such a way that the front sides of the susceptors face each other, and the vertical edges of the susceptors are in contact with each other, thereby forming a substantially enclosed narrow channel between the substrates. The apparatus also includes a number of gas nozzles for injecting reaction gases. The gas nozzles are controlled in such a way that gas flow directions inside the chamber can be alternated, thereby facilitating uniform material deposition. The apparatus includes a number of heating units situated outside the reaction chamber. The heating units are arranged in such a way that they radiate heat energy directly to the back sides of the susceptors.

Abstract: One embodiment of the present invention provides a method for fabricating a solar cell. The method includes: melting a metallurgical-grade (MG) Si feedstock, lowering a single-crystalline Si seed to touch the surface of the molten MG-Si, slowly pulling out a single-crystal Si ingot of the molten MG-Si, processing the Si ingot into single crystal Si wafers to form MG-Si substrates for subsequent epitaxial growth, leaching out residual metal impurities in the MG-Si substrate, epitaxially growing a layer of single-crystal Si thin film doped with boron on the MG-Si substrate, doping phosphor to the single-crystal Si thin film to form an emitter layer, depositing an anti-reflection layer on top of the single-crystal Si thin film, and forming the front and the back electrical contacts.

Abstract: One embodiment of the present invention provides a tunneling junction solar cell. The solar cell includes a base layer, an emitter layer situated adjacent to the shallow counter doping layer, a surface field layer situated adjacent to a side of the base layer opposite to the shallow counter doping layer, a front-side electrode, and a back-side electrode. The base layer includes a shallow counter doping layer having a conduction doping type that is opposite to a remainder of the base layer. The emitter layer has a bandgap that is wider than that of the base layer.

Abstract: One embodiment of the present invention provides a wafer-carrier system used in a deposition chamber for carrying wafers. The wafer-carrier system includes a base susceptor and a top susceptor nested inside the base susceptor with its wafer-mounting side facing the base susceptor's wafer-mounting side, thereby forming a substantially enclosed narrow channel. The base susceptor provides an upward support to the top susceptor.

Abstract: One embodiment of the present invention provides a double-sided heterojunction solar cell. The solar cell includes a lightly doped epitaxial crystalline Si (c-Si) base layer, a front-side passivation layer situated on the front side of the lightly doped epitaxial c-Si base layer, a back-side passivation layer situated on the back side of the lightly doped epitaxial c-Si base layer, a front-side emitter situated on the surface of the front-side passivation layer, a back surface field (BSF) layer situated on the surface of the back-side passivation layer, a front-side electrode, and a back-side electrode.

Abstract: One embodiment of the present invention provides a solar cell. The solar cell includes a photovoltaic structure, a transparent-conductive-oxide (TCO) layer situated above the photovoltaic structure, and a front-side metal grid situated above the TCO layer. The TCO layer is in contact with the front surface of the photovoltaic structure. The front-side metal grid includes a first metal layer comprising Cu, and a second metal layer covering a top surface and sidewalls of the first metal layer. The second metal layer comprises at least one of: Ag and Sn.

Abstract: One embodiment of the present invention provides a heterojunction solar cell. The solar cell includes a metallurgical-grade Si (MG-Si) substrate, a layer of heavily doped crystalline-Si situated above the MG-Si substrate, a layer of lightly doped crystalline-Si situated above the heavily doped crystalline-Si layer, a backside ohmic-contact layer situated on the backside of the MG-Si substrate, a passivation layer situated above the heavily doped crystalline-Si layer, a layer of heavily doped amorphous Si (a-Si) situated above the passivation layer, a layer of transparent-conducting-oxide (TCO) situated above the heavily doped a-Si layer, and a front ohmic-contact electrode situated above the TCO layer.

Abstract: One embodiment of the present invention provides a back junction solar cell. The solar cell includes a base layer, a quantum-tunneling-barrier (QTB) layer situated below the base layer facing away from incident light, an emitter layer situated below the QTB layer, a front surface field (FSF) layer situated above the base layer, a front-side electrode situated above the FSF layer, and a back-side electrode situated below the emitter layer.

Abstract: One embodiment of the present invention provides a photovoltaic module. The photovoltaic module includes an optical concentrator and a tunneling-junction solar cell. The tunneling junction solar cell includes a base layer, a quantum-tunneling-barrier (QTB) layer situated above the base layer, an emitter layer, a front-side electrode, and a back-side electrode.

Abstract: One embodiment of the present invention provides a solar cell. The solar cell includes a metallurgical-grade Si (MG-Si) substrate, a first layer of heavily doped crystalline-Si situated above the MG-Si substrate, a layer of lightly doped crystalline-Si situated above the first heavily doped crystalline-Si layer, a backside ohmic-contact layer situated on the backside of the MG-Si substrate, a second layer of heavily doped crystalline-Si situated above the lightly doped crystalline-Si layer, a first layer of dielectric situated above the second heavily doped crystalline-Si layer, a second layer of dielectric situated above the first dielectric layer, and front electrodes situated above the second dielectric layer.