Etching of GaP surfaces in Aqua regia and in the Bromine‐methanol‐water system

The etchants aqua regia and bromine in methanol in water and in methanol water mixtures were tested on GaP. Aqua regia acted as nonpreferential etchant on (111) B and on {100} planes, the (111) A plane proved to be more resistent to chemical attack. Indications to the formation of a protecting layer was found. Bromine in methanol proved to be preferential etchant for the {100} plane producing a surface geometry characteristic to kinetically determined processes. Increasing the amount of water the (111) B plane could be dissolved also and etch figures characteristic to nonpreferential dissolution began to appear on the {100} and (111) B planes as well. The preferential effect for the {100} plane seems to be related to the water content of the solvent.