Epitaxial growth and assessment of p-type GaAs by chloride VPE

Abstract

A preliminary study of p-type doping in the AsCl 3GaAsH 2 system has been made with the objective of achieving close control of layer thickness, growth rate, doping level, and uniformity to enable double drift GaAs IMPATT layers to be grown in high yield. Because of this well defined objective, the gaseous dopant dimethyl zinc in hydrogen has been used as a doping source as it offers the potential of a large doping range coupled with close control. Our results confirm that DMZ is a useful dopant source in that layers of 10 16 through 3.10 19 cm -3 have been grown with good surface morphology and high mobility. However there is a problem of non-reproducibility at levels below mid 10 17 cm -3. We believe this to be associated with residual water and oxygen within the reactor itself. These problems have been circumvented by the novel use of a doped source to produce a ‘base’ or residual p-type background doping level of 10 16 cm -3. Double drift layers have successfully been produced using a combination of these doping techniques.