LUMINESCENCE-CENTERS INDUCED IN P-TYPE GAASZN BY RADIATION AND HEAT-TREATMENT

Radiation and heat treatments [bombardment with fast neutrons (PHI=10( 15)-10(16) cm-2) and subsequent annealing (T=100-350-degrees-C, t=1 h ) of p-type GaAs:Zn crystals gave rise to a relatively wide luminescen ce band (whose maximum is at hnu(m)=1.38 eV) with a fine structure (at hnu=1.4300, 1.4190, 1.4080, 1.3940, 1.3830, and 1.3720 eV). This lumi nescence band is due to V(As)Zn(Ga) donor-acceptor pairs formed by the radiation-heat treatment: The recombination of electrons and holes bo und to these pairs gives rise to the appearance of a wide structure-fr ee (because of emission of a large number of TA and LO phonons) lumine scence band with hnu(m)=1.38 eV, while annihilation of excitons bound to these pairs is responsible for a structured (because of emission of few TA and LO phonons) luminescence band characterized by a zero-phon on line at hnu(m)=1.430 eV.