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Applied Science and Convergence Technology 2012; 21(6): 342-347

Published online November 1, 2012

Copyright © The Korean Vacuum Society.

Influence of InGaAs Capping Layers on the Properties of InAs/GaAs Quantum Dots

Se Ra Kwon,Mee-Yi Ryu,Jin Dong Song


The optical properties of InAs quantum dots (QDs) grown on a GaAs substrates by migration enhanced molecular beam epitaxy method have been investigated by using photoluminescence (PL) and time-resolved PL measurements. The luminescence properties of InAs/GaAs QDs have been studied as functions of temperature, excitation laser power, and emission wavelength. The PL peak of InAs QDs capped with In0.15Ga0.85As layer (QD2) measured at 10 K is redshifted about 80 nm compared with that of InAs QDs with no InGaAs layer (QD1). This redshift of QD2 is attributed to the increase in dot size due to the diffusion of In from the InGaAs capping layer. The PL decay times of QD1 and QD2 at 10 K are 1.12 and 1.00 ns taken at the PL peak of 1,117 and 1,197 nm, respectively. The reduced decay time of QD2 can be explained by the improved carrier confinement and enhanced wave function overlap due to increased QD size. The PL decay times for both QD1 and QD2 are independent on the emission wavelength, indicating the uniformity of dot size.

Keywords: InAs,양자점,포토루미네션스,시간분해 포토루미네션스,Quantum dots,Photoluminescence,Time-resolved photoluminescence

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