Synchrotron-radiation-induced anisotropic wet etching of GaAs

A room-temperature photoenhanced chemical wet etching process for n-type Ga As using x rays from a synchrotron radiation source is described. HNO3:H2O was used as the etching solution. This process produces smoothly etched sur faces on n-GaAs with a root-mean-square surface roughness of 0.7-2.0 nm, wh ich compares favorably to the unetched surface roughness (0.4 nm). Dependen ce of the etching rate on x-ray intensity and energy, solution concentratio n, and semiconductor doping type are reported. (C) 1999 American Institute of Physics. [S0003-6951(99)04441-1].