Open Access Nano Express

Chirped InGaAs quantum dot molecules for broadband applications

Nirat Patanasemakul, Somsak Panyakeow and Songphol Kanjanachuchai*

Author Affiliations

Department of Electrical Engineering, Faculty of Engineering, Semiconductor Device Research Laboratory (Nanotec Center of Excellence), Chulalongkorn University, Bangkok 10330, Thailand

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Nanoscale Research Letters 2012, 7:207  doi:10.1186/1556-276X-7-207

Published: 6 April 2012

Abstract

Lateral InGaAs quantum dot molecules (QDMs) formed by partial-cap and regrowth technique exhibit two ground-state (GS) peaks controllable via the thicknesses of InAs seed quantum dots (x), GaAs cap (y), and InAs regrowth (z). By adjusting x/y/z in a stacked QDM bilayer, the GS peaks from the two layers can be offset to straddle, stagger, or join up with each other, resulting in multi-GS or broadband spectra. A non-optimized QDM bilayer with a 170-meV full-width at half-maximum is demonstrated. The temperature dependencies of the emission peak energies and intensities from the chirped QDM bilayers are well explained by Varshni's equation and thermal activation of carriers out of constituent quantum dots.

Keywords:
Quantum dot molecules; InAs; InGaAs; Chirp; Broadband; Photoluminescence