Abstract: A process for the plasma deposition of a layer of a microcrystalline semiconductor material is carried out by energizing a process gas which includes a precursor of the semiconductor material and a diluent with electromagnetic energy so as to create a plasma therefrom. The plasma deposits a layer of the microcrystalline semiconductor material onto the substrate. The concentration of the diluent in the process gas is varied as a function of the thickness of the layer of microcrystalline semiconductor material which has been deposited. Also disclosed is the use of the process for the preparation of an N-I-P type photovoltaic device.

Abstract: A P-I-N type photovoltaic device is manufactured by a process wherein the deposition rate of the intrinsic layer is controlled so that a portion of the intrinsic layer which is closest to the P-I interface, and which comprises at least 10% of the thickness of the intrinsic layer, is deposited at a rate which is less than the average rate at which the entire intrinsic layer is deposited.

Abstract: A P-I-N type photovoltaic device is manufactured by a process wherein the deposition rate of the intrinsic layer is controlled so that a portion of the intrinsic layer which is closest to the P-I interface, and which comprises at least 10% of the thickness of the intrinsic layer, is deposited at a rate which is less than the average rate at which the entire intrinsic layer is deposited.

Abstract: Plasma deposition of substantially amorphous semiconductor materials is carried out under a set of deposition parameters which are selected so that the process operates near the amorphous/microcrystalline threshold. This threshold varies as a function of the thickness of the depositing semiconductor layer; and, deposition parameters, such as diluent gas concentrations, must be adjusted as a function of layer thickness. Also, this threshold varies as a function of the composition of the depositing layer, and in those instances where the layer composition is profiled throughout its thickness, deposition parameters must be adjusted accordingly so as to maintain the amorphous/microcrystalline threshold.

Abstract: An N-I-P type photovoltaic device includes a multi-layered body of N-doped semiconductor material which has an amorphous, N doped layer in contact with the amorphous body of intrinsic semiconductor material, and a microcrystalline, N doped layer overlying the amorphous, N doped material. A tandem device comprising stacked N-I-P cells may further include a second amorphous, N doped layer interposed between the microcrystalline, N doped layer and a microcrystalline P doped layer. Photovoltaic devices thus configured manifest improved performance, particularly when configured as tandem devices.

Abstract: An optically enhanced back reflector for a photovoltaic device includes a back reflector layer of aluminum having a multi-layered, reflectivity enhancement member deposed thereon. The multi-layer enhancement member includes at least one pair of first and second layers, the first layer having a low index of refraction and the second layer having a high index of refraction. A layer of transmissive conductive oxide is disposed between the optically enhanced back reflector and the photovoltaic device.

Abstract: Substrate temperatures are maintained above 400.degree. C. During the microwave energized glow discharge deposition of Group IV semiconductor materials. The substrate temperature range provides for the preparation of materials having improved electrical properties. Cell efficiency of a photovoltaic device of the p-i-n type is significantly improved by depositing the intrinsic layer using a microwave generated plasma and a substrate temperature in excess of 400.degree. C. Maximum cell efficiency occurs for depositions carried out in the range of 400.degree.-500.degree. C.

Abstract: High quality semiconductor material is deposited in a microwave energized glow discharge deposition process by energizing a process gas with microwave energy at a power level sufficient to generate a plasma at or near the 100% saturation mode and by impeding access of deposition species to the substrate so as to lower the deposition rate to a value less than that otherwise achieved operating at the 100% saturation mode.

Abstract: The thicknesses of the intrinsic layers of the cells comprising a tandem photovoltaic device are selected so that the cell having the highest quality semiconductor material produces the lowest photocurrent. That cell will then be the dominant cell in the tandem device and its material properties will contribute disproportionately to the overall properties of the tandem device.

Abstract: A back reflector for a photovoltaic device includes an electrically conductive, textured layer and a reflective layer conformally disposed on the textured layer. The reflector may include a protective layer atop the reflective layer. The materials of the reflector are selected to be non-reactive under conditions encountered in the manufacture and use of the photovoltaic device.

Abstract: A method for manufacturing thin film, photovoltaic devices of the type having an intrinsic semiconductor layer disposed between two oppositely charged doped, semiconductor layers. A buffer layer of intrinsic semiconductor material is RF deposited at the junction between a microwave deposited, base intrinsic layer and a layer of doped material. The cell produced by the method of the present invention has enhanced performance characteristics over cells having microwave deposited intrinsic layers with no barrier layers.

Abstract: The glow discharge deposition of thin film materials is most advantageously carried out at a pressure which is less than the pressure of the minimum point on the deposition system's Paschen curve and at a power which is in excess of the minimum power required to sustain a deposition plasma at the particular process pressure.

Abstract: A protective layer is disposed between a silver reflective electrode and a layer of transparent conductive oxide in a photovoltaic device so as to prevent oxidation of the silver. The protective layer may be continuous or discontinuous and may be fabricated from MgF.sub.2, Si.sub.x N.sub.y or T.sub.ix N.sub.y where x and y are positive numbers.

Abstract: Open circuit voltage of photovoltaic devices manufactured by a microwave deposition process is increased by disposing a bias wire in the microwave energized plasma and applying a positive voltage of approximately 100 volts to the wire during only a portion of the time in which the intrinsic semiconductor layer is being deposited.

Abstract: An improved p-type semiconductor alloy film, an improved substantially intrinsic amorphous semiconductor alloy film, improved photovoltaic and photoresponsive devices incorporating such films and r.f. and microwave glow discharge methods for fabricating same. The improved semiconductor alloy films preferably include at least silicon deposited by the glow discharge of a compound containing at least silicon and a boron species that remains substantially monoatomic as it is incorporated into the silicon matrix. The p-type film is particularly stable, is characterized by a non-narrowed band gap, reduced bulk stress, improved morphology, growth and adhesion and reduced peeling and cracking. The substantially intrinsic film is characterized by substantially reduced Staebler-Wronski degradation. The method includes the novel step of introducing a boron species that does not form higher order boron hydrides or other boron polymers or oligomers in the glow discharge plasma.

Abstract: A microwave glow discharge method for the deposition of p-doped semiconductor alloy material, which material is characterized by mono-atomic and tetrahedral incorporation of boron species into the semiconductor host matrix, thereby providing a p-doped semiconductor alloy material characterized by reduced bulk strain, reduced nucleation of undesirable morphological growth, improved adhesion to a substrate and reduced peeling and cracking.

Abstract: Precursor gaseous mixtures from which to glow discharge deposit wide and narrow band gap semiconductor alloy material, said material characterized by improved photoconductivity and stability and improved resistance to photodegradation. There is also specifically disclosed a method of fabricating a narrow band gap semiconductor which method does not suffer from the effects of differential depletion of the components of the precursor gaseous mixture.

Abstract: Precursor gaseous mixtures from which to glow discharge deposit wide and narrow band gap semiconductor alloy material, said material characterized by improved photoconductivity and stability and improved resistance to photodegradation. There is also specifically disclosed a method of fabricating a narrow band gap semiconductor which method does not suffer from the effects of differential depletion of the components of the precursor gaseous mixture.

Abstract: An improved p-type semiconductor alloy film, an improved substantially intrinsic amorphous semiconductor alloy film, improved photovoltaic and photoresponsive devices incorporating such films and r.f. and microwave glow discharge methods for fabricating same. The improved semiconductor alloy films preferably include at least silicon deposited by the glow discharge of a compound containing at least silicon and a boron species that remains substantially monoatomic as it is incorporated into the silicon matrix. The p-type film is particularly stable, is characterized by a non-narrowed band gap, reduced bulk stress, improved morphology, growth and adhesion and reduced peeling and cracking. The substantially intrinsic film is characterized by substantially reduced Staebler-Wronski degradation. The method includes the novel step of introducing a boron species that does not form higher order boron hydrides or other boron polymers or oligomers in the glow discharge plasma.

Abstract: The disclosure is directed to photovoltaic devices having enhanced short circuit currents and efficiencies. The devices are made by depositing on a previously deposited doped amorphous semiconductor alloy layer a body of intrinsic amorphous semiconductor alloys including a first intrinsic layer, adjacent the doped layer, formed from the deposition of a non-etching starting material and a second intrinsic layer different in composition from the first intrinsic layer. The second intrinsic layer preferably includes silicon and fluorine while the first intrinsic amorphous alloy layer does not include fluorine. The first intrinsic layer may be formed by the glow discharge decomposition of silane gas alone. The thicknesses of the first and second intrinsic layers are adjusted so as to match the respective potential drops thereof with the first intrinsic layer being relatively thin as compared to the second intrinsic layer.