Photoluminescence Studies of Si-Doped Epitaxial GaAs Films Grown on (100)- and (111)A-Oriented GaAs Substrates at Lowered Temperatures

Abstract

The electrical properties and photoluminescence features of uniformly Si-doped GaAs layers grown on GaAs substrates with the (100) and (111)A crystallographic orientations of the surface are studied. The samples are grown at the same As4 pressure in the growth temperature range from 350 to 510°C. The samples grown on GaAs(100) substrates possess n-type conductivity in the entire growth temperature range, and the samples grown on GaAs(111)A substrates possess p-type conductivity in the growth temperature range from 430 to 510°C. The photoluminescence spectra of the samples exhibit an edge band and an impurity band. The edge photoluminescence band corresponds to the photoluminescence of degenerate GaAs with n- and p-type conductivity. The impurity photoluminescence band for samples on GaAs(100) substrates in the range 1.30–1.45 eV is attributed to VAs defects and SiAs–VAs defect complexes, whose concentration varies with sample growth temperature. Transformation of the impurity photoluminescence spectra of the samples on GaAs(111)A substrates is interpreted as being a result of changes in the VAs and VGa defect concentrations under variations in the growth temperature of the samples.