Rani Khatwani


December 1988

Document Type


Degree Name



Dept. of Electrical Engineering


Oregon Graduate Center


Epitaxial layers of Gallium Arsenide are grown by organo-metallic chemical vapor phase epitaxy (OMVPE) involving a reaction of arsine and trimethylgallium. These layers are doped n-type with silane. The Hall Coefficient and mobility have been measured in n-type epitaxial gallium arsenide from 365 K to 15 K, and impurity concentrations were computed from the results. Mobilities up to 3745 cm2 V[superscript -1] sec[superscript -1] at 300 K and 11330 cm2 V[superscript -1]sec[superscript -1] at 77 K have been measured. The techniques for determining the concentrations of donors and acceptors in semiconductor samples from Hall effect and resistivity measurements are described. Analyses of the temperature variation of the carrier concentration and mobility permit the determination of ND and NA The separate contributions to carrier scattering have been evaluated. Polar scattering is apparently dominant down to about 100 K. Piezoelectric scattering and deformation potential scattering are significant at 77 K. The Brooks-Herring theory of ionized impurity scattering is shown to give good quantitative agreement with results at low temperatures.





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