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

To determine an optimum initial GaAs surface for application of the Si interface control layer (Si ICL)-based surface passivation method, properties of the (4 x 6) reconstructed Ga-rich (001) surface of GaAs were investigated before and after Si deposition. An UHV-based multi-chamber system was used where samples were prepared by MBE and characterized by STM, XPS, UHV PL, and contactless C-V methods. For comparison, (2 x 4) and c(4 x 4) As-rich surfaces were also prepared. STM observation clarified the microscopic structure of the (4 x 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 x 6) surfaces. Large band-edge PL intensity was obtained on the (4 x 6) surface, and it increased after Si deposition, reaching as high as 8.9 times that of the (2 x 4) surface. UHV contactless C-V measurements indicated low and wide Nss distributions on the initial and Si-deposited (4 x 6) surfaces. Results indicate that the (4 x 6) surface is the most promising surface for application of the Si ICL-based surface passivation process for GaAs. 27 refs.