Journal of Crystal Growth, Vol.378, 470-474, 2013
Temperature dependence of photoluminescence for site-controlled InAs/GaAs quantum dot chains
We study the temperature dependence of the photoluminescence (PL) from InAs quantum dot chains (QDC) grown by MBE on [011]- and [01 (1) over bar]-oriented UV nanoimprint lithography processed groove patterns. We observe an increase of PL intensity from the [01 (1) over bar]-oriented QDCs within the temperature range from 20-70 K, which is attributed to thermally activated carrier transport from small quantum dots accumulated on the sidewalls of the [01 (1) over bar]-oriented grooves to the quantum dots at the bottom of the groove. We utilize a rate equation model to quantitatively analyze the carrier transfer mechanism. Furthermore, we show that the defect related carrier loss mechanism, which accounts for weak PL quenching at low temperatures, is similar for QDCs and self-assembled quantum dots (SAQD) that were used as a reference. The carrier loss mechanism that causes the rapid quenching of SAQD PL at high temperatures is identified as exciton escape, while for the QDCs it is either single carrier escape or escape of uncorrelated electron-hole pairs. This result reveals a significant difference in the carrier dynamics of site-controlled QDCs and SAQDs. (c) 2013 Elsevier B.V. All rights reserved.
Keywords:Nanostructures;Low dimensional structures;Molecular beam epitaxy;Semiconducting III-V materials