Stoichiometric structures of defects in high-purity GaAs grown by the liquid encapsulated Czochralski method

Abstract

We analyze some existing data obtained on a GaAs sample grown by the liquid encapsulated Czochralski (LEC) method from a near-stoichiometric melt after the sample was cycled through various thermal processes. By using the constraint of constant deviation from stoichiometry we are led to suggest that the defects observed or inferred to exist in the sample have the following properties: (1) the acceptor associated with the 1.45-eV photoluminescence signal has the stoichiometric structure of GaAs if doubly charged or of VGaGaAs if singly charged; (2) the (presumed) donor at Ec−0.134 eV has the stoichiometric structure of VAs; (3) another (inferred) acceptor has the stoichiometric structure of VGa; and (4) the very shallow donor at Ec−0.003 eV is the precursor of EL2 and becomes EL2 upon reaction with VGa or its stoichiometric equivalent.