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A Characterization of the Chemical Vapor Deposition of Gallium Arsenide and Indium Phosphide in the Hydride and Chloride Systems.

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Interim rept. Jan 82-Dec 84,

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The fundamental chemistry surrounding the chemical vapor deposition of GaAs and InP in the hydride and chloride processes was investigated. Chemical equilibrium calculations showed that ICl, V4 and V2 were the dominant group III and V species in the vapor phase. These calculations also demonstrated that vapor phase silicon species, formed by the interaction of H2 and HCl with the reactor wall, may be present at compositions up to 1 ppm under typical operation conditions. It was shown that the formation of vapor phase silicon species can be suppressed by the addition of small amounts of H20 or by replacing the H2 carrier gas with an inert. The unintentional incorporation of silicon into III-V epitaxial layers may be decreased by reducing the amount of silicon species in the vapor phase or by shifting these silicon species from hydrogen rich to chlorine rich species through the addition of HCl or VCl3. The use of solid and liquid group III sources in the chloride process was compared. In the GaAs system, the liquid source yielded a much greater degree of supersaturation than did the solid source. This difference was much less pronounced for the InP system. The equilibrium chemistry of the hydride process was found to behave similarly to that of the chloride process. The degree of supersaturation present in the hydride process was found to be lower than that in the chloride process. The thermal decompositions of NH3, PH3, and Ash3 were studied in a constant volume reactor using a mass spectrometer. Keywords III - V semiconductors.

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  • Solid State Physics

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