Heteroepitaxial GaAs on Aluminum Oxide: Electrical Properties of Undoped Films

Abstract
Measurements of the Hall coefficient and resistivity have been carried out on a large number of heteroepitaxial (111) GaAs/(0001) Al2O3 films grown by the trimethylgallium‐arsine process. Nominally undoped films have been produced with average mobilities greater than 5000 cm2/V sec for carrier concentrations between 1015 and 1016 cm−3, the net donor concentrations in the films being determined primarily by the impurities in the reactant gases. The quality and conductivity type can be controlled by the deposition conditions. The GaAs near the Al2O3 interface is found to have inferior electrical properties, with the region nearest the interface exhibiting p‐type conductivity. The dependence of the electrical properties on growth conditions, reactant gas purity, film thickness, and other variables is discussed.

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