Control of initial surface configuration for GaAs-on-Si MBE using a Si buffer layer?

Abstract

Gallium arsenide layers were grown by molecular beam epitaxy on (100) Si substrates misoriented by 1.7° and 4° toward [011], with a thin Si buffer layer deposited before GaAs growth for some samples. Reflection high energy electron diffraction observations showed that the substrates misoriented by 1.7° had mostly single-layer steps, while those misoriented by 4° had mostly double-layer steps, regardless of the conditions for the Si buffer layer growth. For 3 μm thick GaAs layers, the measured full widths at half-maximum of the GaAs (400) X-ray reflection ranged from 680 to 870 μrad (about 140 to 180 arc sec), with linewidths about 15% lower for the layers grown on the 4° misoriented substrates. Photoluminescence spectra for the GaAs layers were dominated by carbon-related luminescence, possibly caused by contamination during in situ annealing cycles. However, a GaAs/AlAs superlattice grown on a GaAs-on-Si buffer layer exhibited a single luminescence peak with a linewidth of 8 meV.