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CVD Growth of Amorphous Hydrogenated Silicon Solar Cells

IP.com Disclosure Number: IPCOM000041439D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Green, DC: AUTHOR [+3]

Abstract

Chemical vapor deposition (CVD) and plasma-enhanced CVD are used for low temperature deposition of hydrogenated amorphous silicon solar cells. The presence of about 10-20 atomic percent Ge will lower the alloy bandgap to a value close to 1.4 eV, and lower, making the cell more effective in using the total solar spectrum. This small amount of GeH4 is admixed into SiH4, the solar cell alloy being prepared by conventional CVD in the 350ŒC temperature range. As an alternative, GeH4 can be mixed with disilane or trisilane and higher silanes, and thermally decomposed in a conventional CVD apparatus using a total pressure of 1 atmosphere, by diluting the mixture in an inert carrier gas, such as He, Ar, H2, or N2 . Low CVD could also be used with no or some inert diluent in these processes, but at a pressure below 1 torr.

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CVD Growth of Amorphous Hydrogenated Silicon Solar Cells

Chemical vapor deposition (CVD) and plasma-enhanced CVD are used for low temperature deposition of hydrogenated amorphous silicon solar cells. The presence of about 10-20 atomic percent Ge will lower the alloy bandgap to a value close to 1.4 eV, and lower, making the cell more effective in using the total solar spectrum. This small amount of GeH4 is admixed into SiH4, the solar cell alloy being prepared by conventional CVD in the 350OEC temperature range. As an alternative, GeH4 can be mixed with disilane or trisilane and higher silanes, and thermally decomposed in a conventional CVD apparatus using a total pressure of 1 atmosphere, by diluting the mixture in an inert carrier gas, such as He, Ar, H2, or N2 . Low CVD could also be used with no or some inert diluent in these processes, but at a pressure below 1 torr. Germanium hydride is less thermally stable then any of the silanes suggested for use. Thus, monogermane will catalyze the decomposition of the higher silanes (or monosilane), allowing film growth at the optimum composition to occur at a much lower temperature. If monogermane does not lower the film growth temperature to the desired level, digermane and higher germanes can be used. In these CVD processes, either hot wall reactors or cold wall reactors can be used in which the substrate temperature is maintained at or below that of the gas. Also, homogeneous CVD, conventional CVD or plasma-enhanced...