Recombination centers in heterostructures investigated by optically and electrically detected magnetic resonance

Using optically and electrically detected magnetic resonance (ODMR and EDMR, respectively), recombination in a (Formula presented) heterostructure is studied. ODMR performed at 35 GHz shows the presence of Ga interstitials in a GaAs quantum well codoped with Si and Be. Depending on the contacts used, EDMR (performed both at 9 and 34 GHz) is able to detect surface defects, intrinsic defects (Ga interstitial and (Formula presented) antisite) as well as the (Formula presented) transition-metal impurity. The location of the paramagnetic states in the heterostructure was determined with EDMR using light of different absorption length for the selective excitation of photoconductivity, combined with a phase shift analysis of the different EDMR signals with respect to the modulation reference. The temperature and microwave power dependence of the EDMR signal amplitude is discussed, providing guidelines for the experimental conditions needed to perform EDMR on GaAs. Finally, using (Formula presented)-band and (Formula presented)-band detection, the defect parameters ((Formula presented)-factor and hyperfine constants) for the Ga interstitial are determined to (Formula presented) and (Formula presented) These results are compared to previous observations.