Surface Fermi level in GaAsSb structures grown by molecular beam epitaxy on InP substrates

摘要

Photoreflectance (PR) spectroscopy is performed to investigate the Fermi level pinning at the surface of GaAsSb, in a series of epitaxial structures with different Sb concentration. PR spectra exhibit Franz-Keldysh oscillations, originating from the built-in electric field in the GaAsSb layer. Experimental results indicate that the surface Fermi level is pinned in the lower half bandgap. The surface Fermi level is determined versus the Sb concentration between 38% and 52%.