Photoluminescence bands of deep centres in neutron-transmutation-doped GaAs
Deep centres in neutron-transmutation-doped semi-insulating GaAs grown by the liquid-encapsulated Czochralski (LEC) technique were studied using the photoluminescence technique. Two photoluminescence bands, PL1 and PL2, were observed at 1.26 and 1.0 eV from the band edge, respectively. The Ge-photoluminescence band is also observed. The Franck-Condon shift was estimated for PL1 and PL2 by utilising the temperature dependence of the linewidth and the configuration coordinate model. The PL1 atomic structure is speculated to be more complex than that of PL2. Both PL1 and PL2 are related to the impurities introduced by the neutron transmutation doping.