Chemical composition, morphology, and deep level electronic states of GaN (0001) (1×1) surfaces prepared by indium decapping

Abstract

Ordered GaN (0001) (1×1) surfaces are prepared after removal from the growth chamber via thermal desorption of a thin In cap layer at 650 °C in combination with one thermal flash of Ga metal to reduce residual O and C contamination. Auger electron spectroscopy (AES) and low energy electron-excited nanoscale luminescence (LEEN) spectroscopy results show that In can prevent contamination during atmospheric exposure if it can cover the surface uniformly. LEEN spectra of the ordered surface show that the In capping layer is desorbed from the GaN without reacting to produce InxGa1−xN or diffusing into the GaN to produce new localized states. Subsequent atomic force microscopy (AFM) measurements reveal an atomically smooth film plus Ga droplets residual to the flash annealing. These results suggest that In decapping may be useful in obtaining clean, LEED-ordered GaN surfaces after transport in air with a minimum of UHV treatment.