Strong Photoluminescence and Low Surface State Densities on Clean and Silicon Deposited (001) Surfaces of GaAs with (4×6) Reconstruction

Abstract

In an attempt to determine an optimum initial GaAs surface for application of the silicon interface control layer (Si ICL)-based surface passivation method, properties of the (4×6) reconstructed Ga-rich (001) surface of GaAs were investigated before and after Si deposition. An ultrahigh vacuum (UHV)-based multi-chamber system was used where samples were prepared by molecular beam epitaxy (MBE), and characterized by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), UHV photoluminescence (PL), and contactless capacitance–voltage (C–V) methods. For comparison, (2×4) and c(4×4) As-rich surfaces were also prepared. STM observation clarified the microscopic structure of the (4×6) surface. XPS measurements confirmed the Ga-rich nature of the initial surface and detected the reduction of band bending on both initial and Si-deposited (4×6) surfaces. A surprisingly large band-edge PL intensity was obtained on the (4×6) surface, and it further increased after Si deposition, reaching as high as 8.9 times that of the (2×4) surface. UHV contactless C–V measurements indicated low and wide Nss distributions on the initial and Si-deposited (4×6) surfaces. All the results consistently indicate that the (4×6) surface is the most promising surface for application of the Si ICL-based surface passivation process for GaAs.