Effects of temperature on transition energies of GaAsSbN/GaAs single quantum wells

Abstract

The energy transitions of GaAsSbN/GaAs strained-layer single quantum wells (QWs), grown by molecular-beam epitaxy, are studied in detail, using photoluminescence (PL) and photoreflectance (PR) spectroscopies. The optical transitions energy observed in the PL and PR spectra of GaAsSbN/GaAs QWs show a strong decrease with a small increase in the N composition. These effects are explained through the interaction between the conduction band and a narrow resonant band formed by nitrogen states in the GaAsSbN alloy. The temperature dependence of ground-state energy of strained-layer QWs is analyzed using the Bose-Einstein relation in the temperature range from 9 to 295 K. The parameters that describe the temperature variations of the ground-state energies are evaluated and discussed.

Tunable dual emission in visible and near-infrared spectra using Co2+-doped PbSe nanocrystals embedded in a chalcogenide glass matrix

“…The increase in the NC size leads to a redshift of the lowest excitonic state of the NCs (quantum size effect). On the other hand, we consider that the position of the energy levels of the Co 2+ ion does not change with the NC size, as observed in other systems with deep ionic electronic states: ZnTe:Mn 2+ and CdSe:Mn 2+ quantum dots, 11,42,43 GaAsSb:N/GaAs quantum wells, 44 and ZnSe:O alloys. 45,46 In addition, one can observe that the excitonic energy transition in our PbSe NCs occurs in the same near-infrared spectral region as the electricdipole allowed 4 A 2 (F) -4 T 1 ( 4 F) transitions of Co 2+ ions in Td sites.…”

“…The PL spectrum of the sample annealed for 500 min has an asymmetric behavior with an apparent exponential tail at the lower energy side, a characteristic of localized excitonic recombinations due to states below the conduction band. 44 We believe that this shoulder at the lower energy side of the PL peak, observed for the sample treated at 500 1C, can be related to 4 T 1 ( 4 F) states after interaction with the extended states of the NC conduction band. Thus, by reducing the energy position of the NC conduction band, after the thermal annealing process, there is an interaction between the 4 T 1 ( 4 F) localized states and the delocalized states of the NC conduction band, so that electrons in the nanocrystal CB can relax by non-radiative recombination with accessible states 4 T 1 ( 4 F) and radiative recombination with the lower 4 A 2 ( 4 F) state.…”

Localized states emission in type-I GaAsSb/AlGaAs multiple quantum wells grown by molecular beam epitaxy

“…In addition, its wide absorption almost covers the solar spectrum ranges, GaAs 1– x Sb x can also be used for solar cells . Compared to the ternary alloy, GaAs 1– x Sb x ‐based multiple quantum wells (MQWs) possess higher emission efficiency and better tunability of the bandgap . However, the optical properties of GaAs 1– x Sb x ‐based MQWs are not yet fully understood, which greatly limits their applications.…”