Properties of Sn-doped GaAs

Abstract

The defect properties of GaAs have been investigated through a process of crystal growth, especially in relation to the change in electrical and luminescence properties and lattice constant due to the deviation from stoichiometry. GaAs crystals were grown from Sn solutions by the temperature gradient method under controlled As pressure from 8.5×10^−‐6 to 4.3×10 Torr. From the photoluminescence measurements, the level which is associated with the As vacancy and Sn is found at 1.34 eV in the low As pressure region. With increasing As pressure, the concentration of the Ga vacancies which behave as acceptors increases and carrier compensation proceeds. The lattice constant is increased by the incorporation of Sn. It also is a function of the As pressure, that is, the Ga vacancy is found to make the lattice constant increase. It can be said that GaAs crystals which deviate from stoichiometry can be obtained when they are grown from Sn solutions under controlled As pressure.