Native Defects in Low Temperature GaAs and the Effect of Hydrogenation

Abstract

AbstractGaAs grown at low temperatures by MBE has been doped with shallow impurities to ∼1019 cm−3. A layer doped with Be acceptors was completely compensated and the simultaneous detection of AsGa0 and AsGa+ confirmed that the Fermi level was close to midgap and that compensation was partly related to AsGa defects. There was no evidence for the incorporation of VGa in this layer. For Si-doped samples, more than 80 % of the donors were compensated and the detection of SiGa-VGa pairs by infrared localized vibrational mode (LVM) spectroscopy indicated that VGa were at least partly responsible. Increasing the Si concentration suppressed the incorporation of AsGa. Exposure of the Be-doped layer to a hydrogen plasma, generated a LVM near 2000 cm−1 which may be the stretch mode of a AsGa-H-VAs defect complex. For Si-doped layers, two stretch modes at 1764 cm−1 and 1773 cm−1 and a wag mode at 779 cm−1 relating to a H-defect complex were detected and we argue that the complex could be a passivated As antisite. The detection of characteristic hydrogen-native defect LVMs may provide a new method for the identification of intrinsic defects.