Abstract
Er-concentration effect in GaAs; Er, O containing charge carriers (n-type, high resistance, p-type) has been studied by X-band Electron spin resonance (ESR) at low temperature (4.7K< T< 18 K). Observed A, B, and C types of ESR signals were identical to those observed previously in GaAs: Er, O without carrier. The local structure around Er-2O centers is not affected by carriers because similar angular dependence of g-values was observed in both cases (with/without carrier). For temperature dependence, linewidth and lineshape analysis suggested the existence of Er dimers with antiferromagnetic exchange interaction of about 7K. Moreover, drastic decrease of ESR intensity for C signal in p-type sample was observed and it correlates with the decrease of photoluminescence (PL) intensity. Possible model for the Er-2O trap level in GaAs: Er, O is discussed from the ESR and PL experimental results. (C) 2014 AIP Publishing LLC.