Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 56: Quantum dots and wires: Preparation and characterization III

HL 56.5: Talk

Friday, March 31, 2006, 12:00–12:15, POT 51

Growth and characterization of self-assembled CdSe quantum dots in MgS barriers — •Arne Gust, Carsten Kruse, Henning Lohmeyer, Kathrin Sebald, and Jürgen Gutowski — Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee, 28359 Bremen, Germany

Up to now it’s only possible to achieve single quantum dot emission from CdSe QDs at low temperatures, which is bleached out for temperatures above 200 K due to the thermal emission of carriers [1]. By embedding the QDs in wide band gap materials such as MgS (5.5 eV) the stronger confinement should stabilize the emission up to room temperature (RT). Samples with additional 5 nm thick MgS barriers surrounding the QD region and a reference sample without barriers have been prepared.

Photoluminescence (PL) measurements were performed at RT in order to be close to the application. The PL spectrum of the reference sample shows a peak with a full-width at half-maximum around 110 meV at RT (emission at 2.38 eV). The emission of the sample including the MgS barriers is shifted by 240 meV to higher energies (2.62 eV) due to the increased confinement. Furthermore the activation energy raised by a factor of 2.5 compared to sample without MgS barriers. Micro-PL measurements on single QDs in dependence on the temperature will be presented in order to quantify the activation energy for different kinds of QD samples.

[1] K. Sebald et al., Appl. Phys. Lett. 81, 2920 (2002).