Temperature-dependent modulated reflectance and photoluminescence of InAs–GaAs and InAs–InGaAs–GaAs quantum dot heterostructures

Abstract

Optical transitions and electronic properties of epitaxial InAs quantum dots (QDs) grown with and without InGaAs strain-relieving capping layer within GaAs/AlAs quantum well (QW) are investigated. Modulated reflectance and photoluminescence (PL) spectroscopy is used to probe the QD-and QW-related interband optical transitions over the temperature range of 3-300 K. The observed spectral features in QDs are identified using numerical calculations in a framework of 8-band k · p method. It is found that covering the dots by a 5 nm-thick InGaAs layer yields the energy red-shift of ground-state transition by ∼ 150 meV. Moreover, the analysis of interband transition energy dependence on temperature using Varshni expression shows that material composition of InAs QDs significantly changes due to Ga/In interdiffusion. A comparison of emission-and absorption-type spectroscopy applied for InAs-GaAs QDs indicates a Stokes shift of ∼ 0.02 meV above 150 K temperature.

Enhancement of photoluminescence of GaAsBi quantum wells by parabolic design of AlGaAs barriers

“…PL signal was detected by InGaAs thermoelectrically cooled photodetector. Conventional setup in details is described elsewhere [22]. Figure 4 shows the PL spectra of QWs structures grown at the same substrate temperature (425 °C), As/Ga BEPR ranging from 0.84 to 1.08 and Bi effusion cell temperature T Bi ranging from 625 °C to 640 °C.…”