Thermally-activated effects on photoluminescence line shape of InAs/GaAs quantum dot heterosystems

¹ Department of Electrical Engineering, Technology and Science Institute of Northern Taiwan, No. 2, Xueyuan Rd., Peitou, 112 Taipei, Taiwan, R.O.C.
² Department of Electronic Engineering, Chang Gung University, No. 259, Wenhwa 1st Rd., Kweishan, 333 Taoyuan, Taiwan, R.O.C.

Corresponding author: gclee@tsint.edu.tw

Received: 2 October 2006
Revised: 7 November 2006
Accepted: 22 December 2006
Published online: 14 February 2007

Abstract

We investigate the temperature dependence of photoluminescence (PL) properties of InAs/GaAs quantum dot (QD) heterostructures. The temperature dependence of the InAs exciton energy and linewidth is found to display a significant difference due to the different dot size distribution. We propose a model, which takes into account the dot size distribution, state filling effect, carrier thermal escaping and retrapping, and electron-phonon scattering, to explain the carriers transferring mechanisms in the QD system. The experimental results are reproduced well by our model. Sample with lower dot size uniformity reveals evident thermal redistribution effect among dots, but the effect is weak for sample with higher dot size uniformity and is overcome by the electron-phonon scattering, which is consistent with the observed monotonically increasing linewidth of PL spectra with temperature.