Growth of InP in a Novel Remote-Plasma MOCVD Apparatus : an Approach to Improve Process and Material Properties

Abstract
Remote plasma metalorganic chemical vapor deposition (RP-MOCVD) technique, though relatively new, is becoming more and more important in the processing of the III-V semiconductor materials and, specifically, of indium phosphide. So far different processes have been designed for (a) the cleaning of InP substrates to remove surface native oxide by reduction with H₂ plasma and (b) the InP deposition under PH₃ plasma preactivation. This paper deals with InP homoepitaxial growth by trimethylindium (TMI) and plasma preactivated PH₃. Optical emission spectroscopy (OES) measurements evidence the presence of PH and PH₂ radicals, and of H-atoms in the plasma phase. Mass spectrometry (MS) sampling close to the growth surface reveals the presence of alchylphosphine ((CH₃)₂PH, CH₃PH₂), indium-phosphorus adduct and biphosphine (P₂H₄), whose relative amounts depend on the growth conditions. Stoichiometric InP epilayers having good structure and morphology, and with a very high photoluminescence intensity are prepared under PH₃ plasma preactivation, even at very low V/III ratio (=20) and reduced temperature ([MATH]550°C).