The Substrate Orientation Effect on Impurity Profiles of Epitaxial GaAs Films

Abstract

Undoped n‐type films have been grown epitaxially on heavily doped n‐type substrates of various crystallographic orientations by the flow method. The thickness of the epitaxial films ranged from 0.5 to 20.5,μ. The impurity profiles of undoped films on the (100) and (110) planes were strongly dependent on the film thickness but independent of the substrate dopants and their concentration. Impurity profiles of films grown on the (111) and planes were independent of the substrate dopants and their concentrations as well as of the film thickness. The steep impurity gradients at the substrate‐film interface exclude the possibility of outdiffusion or autodoping of donors from the substrate. The minimum net donor concentrations obtained were in the low 1015 range. Reverse bias breakdown voltages vary from 5 to 60v for 0.5μ and 6μ thick films, respectively.