Investigations on the HCl gas-phase etching of differently doped and oriented gaas crystals

The influence of the orientation and dopant on the dissolution of GaAs surfaces in H₂–HCl gas mixtures has been investigated. For this purpose the etch rates, temperature regions of different etching behaviour and the corresponding activation energies were determined for temperatures ranging from 540 °C to 945 °C. The etch rate anisotropy is correlated with the three existing temperature regions of different dissolution mechanisms. The orientation-dependent transition temperatures are influenced by the dopant and can be related to the thermodynamic data of the dopant.