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 surfac e network. The composition of the microcrystalline features evolves from As (V) to As(III) with processing time. Spatially localized near-field photolu minescence (PL) spectroscopy of the microcrystalline and porous features de monstrates that the strong visible photoluminescence observed in the far fi eld originates from the mu m-sized crystalline features. The spatial locali zation of the PL on the arsenic oxide microcrystalline features argues that it does not arise from quantum confinement effects, but rather is due to l uminescent features intrinsic to the arsenic oxide microcrystals on the pit ted surface. (C) 1999 American Institute of Physics. [S0003-6951(99)00904-3 ].