Characterization of Mn-centers in vertical gradient freeze-GaAs crystals by electron paramagnetic resonance

Abstract

Four Mn-related EPR centers have been observed in p-type Mn-doped VGF-grown GaAs samples at 4 K. Particularly, a well defined Mn-Mn center at g=2.90 without any disturbance caused by the Mn-0 center could be obtained at 20 K. The observed EPR centers of the Mn-Oa, center at g=2.00, the Mn-Mn at g=2.90, and the Mn-0 at g=5.83 and 2.82 almost disappeared after the thermal treatment and quenching processes at 850 degrees C for 10 min. These thermal behaviors seem to be closely related with the out-diffusion of Ga,, impurity segregation, and the change of the internal stress, respectively. Evidence for the existence of Mn-0 state acting as a charge compensation center in GaAs:Mn is also presented.