Temperature dependence of energy gaps of MBE grown InₓGa₁₋ₓAs/GaAs multiple quantum wells on GaAs(100) substrates

Ten periods of strained InₓGa₁₋ₓAs/GaAs multiple quantum wells (MQWs) with different indium mole fraction x and varying well and barrier widths were grown on GaAs(100) substrates using molecular beam epitaxy. Temperature dependent photoluminescence spectroscopy was used to investigate the optical properties of the MQWs as a function of temperature, particularly, the peak energy of the samples which corresponds to its effective energy gap. The Varshni model of temperature dependence of energy gap was used to fit the effective energy gap of the MQWs. It was found that a shift ΔE from the band gap of bulk InₓGa₁₋ₓAs with the same x corresponds to the energy due to the confinement of the carriers within the well, the strain-induced energies, and the exciton binding energy observed for quantum wells.