STUDY OF DECORATION MICRODEFECTS IN LEC-GROWN SI-DOPED GAAS CRYSTALS BY SELECTIVE PHOTOETCHING AND LASER SCATTERING TOMOGRAPHY

The status of decoration microdefects along the grown-in dislocations was studied in Si-doped LEC GaAs by means of selective DSL photoetching and laser scattering tomography (LST). It will be shown that the existence and type of microdefects in GaAs doped with silicon to give n = 1018 cm-3 is strongly dependent on the melt stoichiometry. In As-rich material numerous arsenic decoration precipitates are present. In Ga-rich material complex decoration defects are formed while in stoichiometric samples no decoration effect could be recognized neither by DSL photoetching nor by LST. In addition in the latter material the presence of very fine matrix microdefects is evidenced by DSL and LST. © 1990.