Near-field photoluminescence of microcrystalline arsenic oxides produced in anodically processed gallium arsenide

Anodic processing of (100) GaAs in aqueous HCl results in the formation of a pitted surface hosting arsenic oxide microcrystals within a porous surface network. The composition of the microcrystalline features evolves from As(V) to As(III) with processing time. Spatially localized near-field photoluminescence (PL) spectroscopy of the microcrystalline and porous features demonstrates that the strong visible photoluminescence observed in the far field originates from the mu m-sized crystalline features. The spatial localization of the PL on the arsenic oxide microcrystalline features argues that it does not arise from quantum confinement effects, but rather is due to luminescent features intrinsic to the arsenic oxide microcrystals on the pitted surface. (C) 1999 American Institute of Physics. [S0003-6951(99)00904-3].