Digital etching of GaAs using Se molecular beam and atomic hydrogen beam

A novel digital etching technique for GaAs was investigated. The GaAs surface was first irradiated by a Se molecular beam to form Ga2Se3 on the surface as a result of the Se–As exchange reaction. The surface was then irradiated by an atomic hydrogen (H*) beam to selectively etch the Ga2Se3 layer. These steps were repeated until etched to the desired depth. An etch rate of about 0.2 nm/cycle was obtained at the substrate temperature of 500 °C. The etch rate was nearly independent of the Se and H* irradiation time, suggesting the involvement of a self‐limiting mechanism in the etching process.