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

Authors :
Leonardo Ranasinghe
Christian Heyn
Kristian Deneke
Michael Zocher
Roman Korneev
Wolfgang Hansen
Source :
Nanomaterials, Vol 11, Iss 3, p 690 (2021)
Publication Year :
2021
Publisher :
MDPI AG, 2021.

Abstract

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.

Details

Language :
English
ISSN :
11030690 and 20794991
Volume :
11
Issue :
3
Database :
Directory of Open Access Journals
Journal :
Nanomaterials
Publication Type :
Academic Journal
Accession number :
edsdoj.9cc924d18014468fa21ceea57d0a42a3
Document Type :
article
Full Text :
https://doi.org/10.3390/nano11030690