Synchrotron-radiation-induced anisotropic wet etching of GaAs

A room-temperature photoenhanced chemical wet etching process for n-type GaAs using x rays from a synchrotron radiation source is described. HNO3:H2O was used as the etching solution. This process produces smoothly etched surfaces on n-GaAs with a root-mean-square surface roughness of 0.7–2.0 nm, which compares favorably to the unetched surface roughness (0.4 nm). Dependence of the etching rate on x-ray intensity and energy, solution concentration, and semiconductor doping type are reported.