Internal quantum efficiency of III-nitride quantum dot superlattices grown by plasma-assisted molecular-beam epitaxy

Gacevic, Zarko and Das, A. and Teubert, J. and Kotsar, Y. and Kandaswamy, P. K. and Kehagias, Th. and Koukoula, T. and Komninou, Ph. and Monroy, E. (2011). Internal quantum efficiency of III-nitride quantum dot superlattices grown by plasma-assisted molecular-beam epitaxy. "Journal of Applied Physics", v. 109 (n. 10); pp.. ISSN 0021-8979. https://doi.org/10.1063/1.3590151.

Description

Title: Internal quantum efficiency of III-nitride quantum dot superlattices grown by plasma-assisted molecular-beam epitaxy
Author/s:
  • Gacevic, Zarko
  • Das, A.
  • Teubert, J.
  • Kotsar, Y.
  • Kandaswamy, P. K.
  • Kehagias, Th.
  • Koukoula, T.
  • Komninou, Ph.
  • Monroy, E.
Item Type: Article
Título de Revista/Publicación: Journal of Applied Physics
Date: 2011
Volume: 109
Subjects:
Faculty: E.T.S.I. Telecomunicación (UPM)
Department: Ingeniería Electrónica
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

We present a study of the optical properties of GaN/AlN and InGaN/GaN quantum dot (QD) superlattices grown via plasma-assisted molecular-beam epitaxy, as compared to their quantum well (QW) counterparts. The three-dimensional/two-dimensional nature of the structures has been verified using atomic force microscopy and transmission electron microscopy. The QD superlattices present higher internal quantum efficiency as compared to the respective QWs as a result of the three-dimensional carrier localization in the islands. In the QW samples, photoluminescence (PL) measurements point out a certain degree of carrier localization due to structural defects or thickness fluctuations, which is more pronounced in InGaN/GaN QWs due to alloy inhomogeneity. In the case of the QD stacks, carrier localization on potential fluctuations with a spatial extension smaller than the QD size is observed only for the InGaN QD-sample with the highest In content (peak emission around 2.76 eV). These results confirm the efficiency of the QD three-dimensional confinement in circumventing the potential fluctuations related to structural defects or alloy inhomogeneity. PL excitation measurements demonstrate efficient carrier transfer from the wetting layer to the QDs in the GaN/AlN system, even for low QD densities (~1010 cm-3). In the case of InGaN/GaN QDs, transport losses in the GaN barriers cannot be discarded, but an upper limit to these losses of 15% is deduced from PL measurements as a function of the excitation wavelength.

More information

Item ID: 11862
DC Identifier: http://oa.upm.es/11862/
OAI Identifier: oai:oa.upm.es:11862
DOI: 10.1063/1.3590151
Official URL: http://jap.aip.org/resource/1/japiau/v109/i10/p103501_s1
Deposited by: Memoria Investigacion
Deposited on: 15 Oct 2012 09:25
Last Modified: 21 Apr 2016 11:02
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