Liquid phase epitaxial growth of Zn and S doped GaAs

Abstract

Zn-doped liquid phase epitaxial GaAs layers, in which Zn is added in a Zn/Ga weight ratio varying from 1.1 X 10 -4 to 1 X 10 -2, are grown at temperatures of 700, 800 and 900°C. The effect of Zn evaporation from the melt before epitaxial growth was examined. It was found that the relation between the carrier density, p, in the Zn-doped GaAs layers and the heating time, t, of the melt prior to the growth is expressed by p = p o exp(- CP Zn t ), where P Zn is the vapor pressure of Zn and C is a cons tant. Sulfur doped GaAs layers are grown at 800°C from Ga solutions in a hydrogen gas flow containing H 2S in concentrations ranging from 0.09 to 1000 ppm. The results show that the carrier density in the S-doped layers varies between 1 X 10 16 and 3 X 10 18 cm -3 at room temperature and that broad bands in the photoluminescence spectrum appear at longer wavelengths together with near- band-gap emission for highly S-doped layers. It seems that the broad bands result from the formation of the deep levels caused by the incorporated S.