4.7 Article

Luminescence from Droplet-Etched GaAs Quantum Dots at and Close to Room Temperature

期刊

NANOMATERIALS
卷 11, 期 3, 页码 -

出版社

MDPI
DOI: 10.3390/nano11030690

关键词

semiconductor; nanostructuring; quantum dot; self-assembly; droplet etching; room temperature; photoluminescence

资金

  1. Deutsche Forschungsgemeinschaft [HE 2466/2-1, HA 2042/8-1]
  2. European Union [721394]
  3. BMBF Forschungslabor Mikroelektronik Deutschland ForLab

向作者/读者索取更多资源

This study investigates photoluminescence emission from self-assembled strain-free GaAs quantum dots in refilled AlGaAs nanoholes at and close to room temperature. Two major obstacles for room temperature operation are identified, and optimized sample designs and excitation wavelengths are shown to enable room temperature emission from the quantum dots.
Epitaxially grown quantum dots (QDs) are established as quantum emitters for quantum information technology, but their operation under ambient conditions remains a challenge. Therefore, we study photoluminescence (PL) emission at and close to room temperature from self-assembled strain-free GaAs quantum dots (QDs) in refilled AlGaAs nanoholes on (001)GaAs substrate. Two major obstacles for room temperature operation are observed. The first is a strong radiative background from the GaAs substrate and the second a significant loss of intensity by more than four orders of magnitude between liquid helium and room temperature. We discuss results obtained on three different sample designs and two excitation wavelengths. The PL measurements are performed at room temperature and at T = 200 K, which is obtained using an inexpensive thermoelectric cooler. An optimized sample with an AlGaAs barrier layer thicker than the penetration depth of the exciting green laser light (532 nm) demonstrates clear QD peaks already at room temperature. Samples with thin AlGaAs layers show room temperature emission from the QDs when a blue laser (405 nm) with a reduced optical penetration depth is used for excitation. A model and a fit to the experimental behavior identify dissociation of excitons in the barrier below T = 100 K and thermal escape of excitons from QDs above T = 160 K as the central processes causing PL-intensity loss.

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