Effects of the V/III flux ratio on the Curie temperature of GaMnAs

Abstract

We investigated the effects of V/III flux ratios on the Curie temperature, T-C, in Ga1-xMnxAs layers with Mn mole fractions of x = 0.03 and 0.05. Changes in the T-C are observed by varying V/III ratio with a fixed Mn mole fraction. The T-C in the sample grown with a lower V/III ratio (similar to25) is found to be higher than that in the sample grown with a higher V/III flux ratio (similar to34) at a fixed high Mn concentration (x = 0.05). Although the Mn concentration is increased, the T-C is not much changed when the V/III ratio is high (similar to34). These results can be explained by the existence of low-temperature growth defects, which are considered to have the main effects on the electrical and the magnetic properties of the GaMnAs layers. We elucidated the relevant defects by employing thermal annealing processes and by obtaining photoluminescence spectra.