Reduction of deep levels in MOCVD-regrown AlxGa1−x as interfaces by (NH4)2S passivation and in-situ HCl etching

Abstract

The effects of surface preparation usinginsitu HCl etching and (NH4)2S passivation of AlxGa1-xAs episurfaces prior to regrowth by MOCVD are analyzed by deep level transient spectroscopy (DLTS), electrochemical profiling (C-V) and room-temperature photoluminescence (PL). Four electron traps were found from the DLTS measurements; a DX-center and three traps previously reported for oxygen-contaminated MOCVD systems. Electrical and optical measurements on quantum well lasers containing a regrown interface in the optical confinement region are also presented. It is demonstrated that both (NH4)2S passivation and HClin-situ etching improve the electrical and optical quality of the regrown AlxGa1-xAs interfaces, with the best results being obtained when the two methods are used in tandem.