Investigation of p-CdTe and p-ZnxCd1-xTe single crystals by ps-laser-induced gratings and by photoluminescence

From the measured erasure times of transient gratings created in the volume and on the surface of non-intentionally doped p-type CdTe and ZnxCd1-xTe (x ≤ 0.11) single crystals the free-carrier lifetime and the surface recombination velocity at room temperature are determined, respectively. The erasure time of the surface grating in CdTe is found to be 130 ps, which is one order smaller than that of the volume grating. A lifetime shortening is observed in mixed crystal. Moreover, using cw-laser excitation the samples are characterized additionally by photoluminescence investigation at low temperatures to test the quality, to determine the mole fraction, and to identify impurities. The A0X-line observed is interpreted as due to a single acceptor on Te site. In the mixed crystals at x ≥ 0.09 the two-mode behaviour of LO-phonons and an up to now not observed splitting of the A0X-line are found. (author)