Persistent template effect in InAs/GaAs quantum dot bilayers

• Published in: Journal of applied physics 2010-06, Vol.107 (11), p.113502-113502-6
• Main Authors: Clarke, E., Howe, P., Taylor, M., Spencer, P., Harbord, E., Murray, R., Kadkhodazadeh, S., McComb, D. W., Stevens, B. J., Hogg, R. A.
• Format: Article
• Language: English
• Subjects: ARSENIC COMPOUNDS; ARSENIDES; CRYSTAL GROWTH; CRYSTAL GROWTH METHODS; ENERGY RANGE; EPITAXY; GALLIUM ARSENIDES; GALLIUM COMPOUNDS; INDIUM ARSENIDES; INDIUM COMPOUNDS; INTERFACES; LAYERS; MATERIALS; MATERIALS SCIENCE; MEV RANGE; MOLECULAR BEAM EPITAXY; NANOSCIENCE AND NANOTECHNOLOGY; NANOSTRUCTURES; OPTICAL PROPERTIES; PHYSICAL PROPERTIES; PNICTIDES; QUANTUM DOTS; SEMICONDUCTOR MATERIALS; TEMPERATURE DEPENDENCE; WAVELENGTHS
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.3429226

The dependence of the optical properties of InAs/GaAs quantum dot (QD) bilayers on seed layer growth temperature and second layer InAs coverage is investigated. As the seed layer growth temperature is increased, a low density of large QDs is obtained. This results in a concomitant increase in dot size in the second layer, which extends their emission wavelength, reaching a saturation value of around 1400 nm at room temperature for GaAs-capped bilayers. Capping the second dot layer with InGaAs results in a further extension of the emission wavelength, to 1515 nm at room temperature with a narrow linewidth of 22 meV. Addition of more InAs to high density bilayers does not result in a significant extension of emission wavelength as most additional material migrates to coalesced InAs islands but, in contrast to single layers, a substantial population of regular QDs remains.