OBSERVATION OF CR3+ ELECTRON-PARAMAGNETIC-RESONANCE CENTER IN GAAS CO-DOPED WITH CR AND IN

We have observed a well-defined Cr3+(3d3) electron paramagnetic resonance signal at 4 K in vertical gradient freeze semi-insulating GaAs single crystal through a co-doping with Cr and In. On the basis of analyzing the rotation pattern of the Cr3+ center, the z-axis of the D-tensor for Cr3+ center in the principal axis system was found to be parallel to the [110BAR] direction in the crystal. The g tensor and zero field splitting parameters are determined with monoclinic spin Hamiltonian. The local site symmetry of the Cr3+ center in GaAs:Cr, In is different from that reported in GaAs:CT. The lowering of the substitutional Cr3+ at Ga site in symmetry from cubic (T(d)) to monoclinic field (C2) seems to be attributed to the change of the local field due to an In atom existed in the 2nd nearest neighbor.