SYMMETRY OF OPTICALLY-ACTIVE YB-RELATED CENTERS IN INP AND IN1-XGAXP (X-LESS-THAN-OR-EQUAL-TO-0.13)

The symmetry of Yb3+-related luminescent centers in InP and In1-xGaxP layers with alloy composition less than x=0.13 is studied using polari zed excitation spectroscopy. An induced polarized luminescence under a bove gap excitation is detected and is explained in terms of an excita tion mechanism involving 4f-->5d shell electron transitions. It is sho wn that the Yb3+-related centers responsible for 1.220-1.237 eV lumine scence are optically anisotropic With C3v symmetry or its subgroup. Th e effect of alloy composition on the symmetry of Yb centers is analyze d in terms of the Yb3+-Ga(In) defect model.