Interband transition studies on CdxZn1−xTe/ZnTe step quantum wells under applied electric fields

Abstract

Photoluminescence (PL) measurements were carried out to investigate the interband transitions in CdxZn1−xTe/ZnTe asymmetric step quantum wells with and without an applied electric field. Transmission electron microscopy showed that the CdxZn1−xTe/ZnTe step quantum wells consisted of a shallow Cd0.1Zn0.9Te well and a deep Cd0.18Zn0.82Te well bound by two thick ZnTe barriers. The results for the PL data at 300 K for several applied electric fields showed that the excitonic transition from the first electronic state to the first heavy-hole state shifted to the larger energy side as the applied electric field increased. The electronic subband energies and the wave functions in the step quantum wells were calculated by an envelope-function approximation method, taking into account the strain effects, and the calculated values of the interband transitions were in qualitative agreement with those obtained from the PL measurements. The Stark shift of the step quantum well was much more sensitive to the applied electric field than that of the single quantum well. These results indicate that CdxZn1−xTe/ZnTe step quantum wells hold promise for potential applications such as new types of modulators and quantum-well infrared photodetectors in the blue–green region of the spectrum.