Temperature dependence of the photoluminescence energy of CdTe/ZnTe heterostructures

Abstract

The photoluminescence (PL) energy was calculated for the heterostructure CdTe/ZnTe, where the emission is based on quantum confinement. This system was studied because it yields a high-intensity emission, covering a wide range of the visible spectrum wavelengths. Our calculations obtained the energy of the fundamental state for electrons and holes, as well as the PL energy using both the Varshni and Manoogian–Woolley formalisms taking into consideration the effects of strain. The Varshni and M–W formalisms for the study of the band gap energy as a function of the temperature differ for high- and low-temperature values. This is because the M–W model takes into account the thermal dilatation and electron–phonon interaction through the U and V parameters. The calculations used quantum wells based on the CdTe/ZnTe heterostructure with different thicknesses (number of monolayers) and involved analyzing the dependence on the thickness and barrier height. The aims of this study were analyzing how the shift occurs in the emission color while increasing of the quantum-well width, and studying the temperature dependence of two different formalisms. The PL energy as a function of the quantum well thickness presents an inflection point at around five monolayers, which is in agreement with reports regarding the critical thickness of heterostructure CdTe/ZnTe. This inflection point is modified when the strain in the heterostructure is taken into account.