Deep electronic states near the surface of (In,Ga)P layers grown by MOVPE on GaAs

Metal-semiconductor contacts are used to examine deep electronic states nea r the (In,Ga)P surface by deep-level transient Fourier spectroscopy. Toward s the as-grown (In,Ga)P surface, the In mole fraction increases due to para sitic indium deposited from the horizontal reactor during cooling after gro wth. This process is accompanied by compressive strain, which leads to the formation of several deep-level defects near the surface of Si- as well as Zn-doped (In,Ga)P layers and their successive diffusion into the epitaxial layer. In contrast, Si-doped (In,Ga)P capped by a GaAs layer is practically free of deep-level defects. In the bulk of Zn-doped layers, a dominant hol e trap is found at 0.91 eV with or without a GaAs cap layer. (C) 1999 Elsev ier Science B.V. All rights reserved.