Effects of band anticrossing on the temperature dependence of the band gap of ZnSe_1−xO_xalloys

Abstract

Interband optical transitions in highly mismatched ZnSe 1−x O x alloys with up to 1.35% O content have been studied with photoreflectance. Incorporation of oxygen results in a pronounced reduction of the temperature dependence of the energy gap of the alloy. A detailed analysis of the experimental data shows that the reduction in the temperature dependence of the band gap with increasing O content can be explained by the band anticrossing interaction between the temperature dependent conduction band of ZnSe host matrix and the temperature independent on the absolute scale energy highly localized O states. It has been shown that the assumption of constant energy separation between the oxygen level and the valence band cannot be applied in order to achieve good quantitative agreement of the theoretical and experiment data.

Role of Exciton Binding Energy on LO Phonon Broadening and Polaron Formation in (BA)2PbI4 Ruddlesden–Popper Films

“…Here, it appears that the relative shifts in (P1) and (P3) rather reflect a subtle relationship between the more strongly bound excitonic complex (P3) and the more weakly bound complex (P1). This is analogous to the effects observed in systems with large densities of isoelectronic transitions close to the continuum such as the dilute nitrides − and II–VI oxides …”

“…This is analogous to the effects observed in systems with large densities of isoelectronic transitions close to the continuum such as the dilute nitrides 43−45 and II−VI oxides. 46 As the temperature increases, the transitions (P3) and (P1) begin to converge, indicating once more that a more uniform structural configuration begins to evolve until at T ∼ 280 K 23,37 the relaxation (reorientation) of the inorganic framework results in a macroscopic change in the band gap with only a single excitonic feature at 2.4 eV.…”

On the predictive, quantitative properties of the amphoteric native defect model

“…We included effects of nonparabolic conduction bands and determined the positions of the conduction and the valence band edges relative to E FS as a function of temperature by interpolation from the binary materials. The temperature dependence of the conduction band edges relative to the vacuum level comes mainly from the thermal expansion of the lattice parameter [17]. We have calculated those shifts for the related binary semiconductors using equation (6) in [17], which depends on the fractional expansion of the lattice parameter and the conduction band deformation potential.…”

“…The temperature dependence of the conduction band edges relative to the vacuum level comes mainly from the thermal expansion of the lattice parameter [17]. We have calculated those shifts for the related binary semiconductors using equation (6) in [17], which depends on the fractional expansion of the lattice parameter and the conduction band deformation potential.…”