ABSTRACT
Another weak peak at 1.569 eV is LO photon replica of the dominant (A0 , X) transition. (A0 ,X-LO) slightly increases with (A0 , X). The bands at 1.541 and 1.549 eV are attributed to the donor-acceptor pair (DAP) and free-to-bound transitions ( e, A 0 ), respectively. The peak intensity of (DAP) decreases and finally almost vanished with increasing the thickness and adding to the (e, A0 ) peak. Shin [10] and Hallidey [li] also reported this free to bound (e, A0 ) transition at 1.549 eV between a free electron and an acceptor complex consisting of a Cd vacancy and two shallow donors (VCd-2D).
