Interband transition and electronic subband studies in [formula omitted] strained single and double quantum wells grown by double-well temperature-gradient vapor deposition

Abstract

Several kinds of CdTeZnTe strained single and double quantum well structures were grown on GaAs (100) substrates by the simple method of double-well temperature-gradient vapor-transport deposition. X-ray diffractometry and transmission electron microscopy measurements were performed to characterize the structural properties of the CdTeZnTe quantum wells. Photoluminescence (PL) measurements on the CdTeZnTe strained single quantum wells showed that the sharp excitonic peaks corresponding to the transitions from the first electronic subband to the first heavy-hole band were shifted to lower energy with increasing well width. The results for the PL data on the CdTeZnTe double quantum wells at 15 K demonstrated clearly that the transition behavior from coupled to uncoupled peaks depends on the ZnTe embedded potential barrier thickness. Photoreflectance measurements showed several resonant excitations in the CdTeZnTe single and double quantum wells. Electronic subband energies and wavefunctions were calculated by an envelope function approximation taking into account the strain effects, and the theoretical values of the interband transitions were in good agreement with those obtained from the experimental measurements. The coupling behavior between two CdTe wells separated by a ZnTe barrier layer in the double quantum wells investigated by theoretical calculations was in good qualitative agreement with those obtained from experimental data.