Photoluminescence scanning on InAs/InGaAs quantum dot structures

• Published in: Applied surface science 2006-05, Vol.252 (15), p.5542-5545
• Main Authors: Dybiec, M., Borkovska, L., Ostapenko, S., Torchynska, T.V., Casas Espinola, J.L., Stintz, A., Malloy, K.J.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; InAs quantum dots; Physics; PL scanning spectroscopy
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2005.12.125

The photoluminescence spectra of InAs quantum dots (QDs) embedded into four types of In x Ga 1− x As/GaAs ( x = 0.10, 0.15, 0.20 and 0.25) multi quantum well MBE structures have been investigated at 300 K in dependence on the QD position on the wafer. PL mapping was performed with 325 nm HeCd laser (35 mW) focused down to 200 μm (110 W/cm 2) as the excitation source. The structures with x = 0.15 In/Ga composition in the In x Ga 1− x As capping layer exhibited the maximum photoluminescence intensity. Strong inhomogeneity of the PL intensity is observed by mapping samples with the In/Ga composition of x ≥ 0.20–0.25. The reduction of the PL intensity is accompanied by a gradual “blue” shift of the luminescence maximum at 300 K as follows from the quantum dot PL mapping. The mechanism of this effect has been analyzed. PL peak shifts versus capping layer composition are discussed as well.