A review of etching and defect characterisation of gallium arsenide substrate material

Abstract Emphasis is placed on the practical aspects of the etching of GaAs substrates, including procedures for the preparation of polished substrates and for the revelation of defects by selective attack. Basic information on the crystallography of GaAs and its effects on the structures of defects is considered, with particular reference to the reactions of etching solutions at the defects. Problems associated with the introduction of mechanical damage at substrate surfaces and its detection and elimination by various etch treatments is discussed. Etch compositions for the preparation of various surface finishes are described and classified. Complex etch features resulting from the attack of particular etchants at substrate surfaces are interpreted in terms of defect structures. Evidence is presented which demonstrates that correct surface treatment is necessary prior to the application of certain defect etches for their successful operation.