Stress effects on the photoluminescence energies and binding energies of excitons in ultra-thin ZnTe/CdTe/ZnTe quantum wells

• Using the variational method and the effective mass and parabolic band approximations, electron and heavy-hole ground-state energies and exciton and photoluminescence energies are calculated in ultra-thin quantum wells of CdTe/ZnTe heterostructures.
• The maximum exciton binding energy bE was found to lie between 20 and 21.5 meV depending on the value of parameter K.
• The critical thickness of the system was found to be five monolayers, based on the exciton binding energy, or seven monolayers, based on the free-carrier ground-state energy.
• It is proposed that in the absence of stress effects, the valence band discontinuity is 0.1hgVE≤Δ, given that when 0hV=, weak exciton effects are observed.

Using the variational method and the effective mass and parabolic band approximations, electron and heavy-hole ground-state energies and exciton and photoluminescence energies are calculated in ultra-thin quantum wells of CdTe/ZnTe heterostructures. The results indicate dependencies on the well width, the barrier height, and stress-related effects and occur because the wave functions of both free carriers and those bound in exciton form determine the system energy and are shaped by the geometry of the well. Critical system thicknesses were estimated for the point at which stress effects become negligible: a value of five monolayers was obtained based on the exciton binding energy, and a value of seven monolayers was obtained based on the free-carrier ground-state energy.