Diffusion of zinc into gaas layers grown by molecular beam epitaxy at low substrate temperatures |
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Authors: | Y K Sin Y Hwang T Zhang R M Kolbas |
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Institution: | (1) Department of Electrical and Computer Engineering, North Carolina State University, 27695-7911 Raleigh, N.C. |
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Abstract: | We report the diffusion of zinc into low temperature (LT) GaAs grown by MBE at 200° C, the problems associated with using a silicon nitride film directly deposited on the LT GaAs as a Zn diffusion mask, and several schemes to avoid the problems. The Zn diffusion coefficient is measured (sealed-ampoule technique) to be about one order of magnitude higher in the LT GaAs than in normal GaAs, attributed to a large quantity of defects including arsenic antisites (AsGa) in the LT GaAs. The effectiveness of silicon nitride as a Zn diffusion mask depends if the mask is deposited directly on the LT GaAs. The failure of the nitride directly deposited on the LT GaAs to stop the Zn is attributed to arsenic atoms outdiffusing from the As-rich LT GaAs (about 1 at. % excess As) into the nitride. Several structures are introduced including a 100-Å thick GaAs layer on the LT GaAs that are effective in preserving the diffusion mask properties of the silicon nitride. |
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Keywords: | Zn diffusion LT GaAs Si3N4 MBE |
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