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 x 6) reconstructed Ga-rich (001) surface of GaAs were investigated before and after Si deposition. An ultra-high vacuum-based multi-chamber system was used where samples were prepared by molecular beam epitaxy, and characterized by scanning tunnelling microscopy, X-ray photoelectron spectroscopy, ultra-high vacuum photoluminescence and contactless capacitance–voltage (C–V) methods. For comparison, (2 x 4) and c(4 x 4) As-rich surfaces were also prepared. Scanning tunnelling microscopic observation clarified the microscopic structure of the (4 x 6) surface. X-ray photo-electron spectroscopy 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. A surprisingly large band-edge photoluminescence intensity was obtained on the (4 x 6) surface, and it further increased after Si deposition, reaching as high as 8.9 times that of the (2 x 4) surface. Ultra-high vacuum contactless C–V measurements indicated low and wide Nss distributions on the initial and Si-deposited (4 x 6) surfaces. All the results consistently indicate that the (4 x 6) surface was the most promising surface for application of the Si ICL-based surface passivation process for GaAs.

Strong Photoluminescence and Low Surface State Densities on Clean and Silicon Deposited (001) Surfaces of GaAs with (4 x 6) Reconstruction. Y.Nakano, N.Negoro, H.Hasegawa: Japanese Journal of Applied Physics, 2002, 41, 2542-7