Photoluminescence characterization of air exposed AlGaAs surface and passivated ex situ by ultrathin silicon interface control layer

Using the photoluminescence surface state spectroscopy (PLS3) technique, attempts were made to determine the surface state density (N-ss) distribution on AlxGa1-xAs (x approximate to 0.3) surfaces passivated by the Si interface control layer (ICL) technique. Air-exposed AlGaAs epitaxial wafers which are technologically important for fabrication of various devices were passivated ex situ by forming a SiO2/Si3N4/Si ICL/AlGaAs structure after the HCl treatment and their photoluminescence behavior was investigated in detail. The result of the PLS3 analysis indicated that Si ICL-based passivation reduces the minimum interface state density value down to 10(10) cm(-2) eV(-1) range. Some indication was also obtained that further improvements are possible by using electron cyclotron resonance (ECR)-enhanced N-2 plasma for Si3N4/Si ICL interface formation. (C) 1998 Elsevier Science B.V. All rights reserved.