Nonstoichiometric defects in GaAs and the EL2 bandwagon

In the present paper, an attempt is made to formulate a common framework for a discussion of nonstoichiometric defects, especially EL2 and dislocations. An outline is provided of the most important settled and unsettled issues, taking into account not only fundamental interests, but also urgent needs in advancing IC technology. Attention is given to stoichiometry-controlled compensation, the expected role of melt stoichiometry in electrical conductivity for the basic atomic disorders, defect equilibria-dislocations and EL2, and current issues pertaining to the identification of EL2. It is concluded that nonstoichiometric defects play a critical role in the electronic properties of GaAs and its electronic applications. Very significant progress has been recently made in learning how to adjust melt stoichiometry in order to maximize its beneficial effects and minimize its detrimental ones.