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Issue Eur. Phys. J. Appl. Phys.
Volume 37, Number 1, January 2007
Page(s) 15 - 18
Section Semiconductors and Related Materials
DOI 10.1051/epjap:2007006
Published online 26 January 2007

Eur. Phys. J. Appl. Phys. 37, 15-18 (2007)
DOI: 10.1051/epjap:2007006

Contribution of long lived metastable states to the PL of InP dots in indirect band-gap barrier layers

R. Seguin1, T. Guillet1, T. Taliercio1, P. Lefebvre1, T. Bretagnon1, X.B. Zhang2, J.H. Ryou2 and R.D. Dupuis2

1  Groupe d'Étude des Semiconducteurs - CNRS - Université Montpellier II. CC074, 34095 Montpellier Cedex 5, France
2  School of Electric and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA

thierry.taliercio@ges.univ-montp2.fr

(Received: 13 July 2006 / Received in final form: 19 September 2006 / Accepted: 13 October 2006 / Published online: 26 January 2007)

Abstract
We report continuous wave and time resolved photoluminescence studies of self-assembled InP quantum dots grown by metalorganic chemical vapor deposition. The quantum dots are embedded into indirect band-gap In0.5Al0.5P layers or In0.5Al0.3Ga0.2P layers with a conduction band line-up close to the direct-to-indirect crossover. As revealed by photoluminescence spectra, efficient interdiffusion of species from the barrier layers produces (Al,In)P or (Al,Ga,In)P-dots. This interdiffusion creates potential barriers that are repulsive for electrons of X valleys around the QDs. Both samples show a fast exponential decay component with a time constant between 0.5 and 0.7 ns. In addition, the sample with indirect band gap matrix shows a slow non-exponential time-decay, which is still visible after more than 100 $\mu $s. The fast component is attributed to direct recombination of electron-hole pairs in the dots whilst the slow component, which follows a power law t-0.75 results from recombination of holes in the dots and electrons in metastable states around the dots.

PACS
78.67.Hc - Quantum dots.
78.47.+p - Time-resolved optical spectroscopies and other ultrafast optical measurements in condensed matter.
78.55.Cr - III-V semiconductors.

© EDP Sciences 2007


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