Intersublevel Relaxation Dependence of Carrier Hopping in self-organized InAs Quantum Dot Heterostructures

Hui-Tang Shen 3Ya-Fen Wu 1Yung-Hsiang Lin 3Chao-Ching Cheng 3Ray-Ming Lin 3Tzer-En Nee 3Nien-Tze Yeh 2

1. Kuang-Wu Institute of Technology, No. 151, Yide St., Beitou Chiu, Taipei 112, Taiwan
2. Telecommunication Laboratories, Chunghwa Telecom Co., Ltd., 12, Lane 551, Min-Tsu Road Sec.5, Yang-Mei 326, Taiwan
3. Chang Gung University, Department of Electronic Engineering, 259 Wen-Hwa 1st Road, Kwei-Shan, Taiwan

Abstract

A reduction of dimensionality of the electron motions in nano-structures brings new phenomena in semiconductor physics. The correlations between intersublevel relaxation and interdot carrier hopping are an important issue for quantum dot (QD) heterosystems. All InAs QD samples grown on (100) 2o-titled toward (111)A Si-doped GaAs substrates with different size uniformity and dot density were carried out by metal-organic chemical vapor epitaxy (MOVPE). The observed photoluminescence redshifts for all samples investigated here revealed that the QD formation was controlled by the growth conditions. The full width at half maximum (FWHM) depended on dot size uniformity at low temperatures. With increasing temperature, the hot carriers on the excited states overcame the potential barrier to redistribute in heterodot system. Moreover, not only phonon bottleneck effect, but also size variation led to the observed abnormal shrinkage of FWHM. Considering carrier-photon rate equations, interestingly, the longer relaxation time to the ground state of ~200 ps was obtained in the QD samples with more size-inhomogeneity, while the shorter time of ~30 ps in those with more size-homogeneity. Up to temperature of 325 K, the FWHM for all the confined states increased with temperatures was dominantly due to both the electron-phonon scattering as well as thermal distribution. The images taken from the transmission electron microscopy were also shown.

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Presentation: oral at E-MRS Fall Meeting 2003, Symposium F, by Tzer-En Nee
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-28 10:05
Revised:   2009-06-08 12:55
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