Chirped InGaAs quantum dot molecules for broadband applications.

Nirat Patanasemakul,Somsak Panyakeow,Songphol Kanjanachuchai

doi:10.1186/1556-276x-7-207

Nirat Patanasemakul, Somsak Panyakeow + Show 1 more

Open Access

https://doi.org/10.1186/1556-276x-7-207

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Journal: Nanoscale Research Letters	Publication Date: Apr 6, 2012
Citations: 3	License type: cc-by

Affiliation: Chulalongkorn University

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.

Highlights

To reduce the stack number in chirped Quantum dot (QD) structures without compromising bandwidth, the QDs can be replaced by certain types of lateral quantum dot molecules (QDMs)
We propose and demonstrate an alternative chirped structure whose active layer is a lateral InGaAs QDM bilayer
A typical QDM layer is formed via the partial-cap and regrowth technique [15] where x monolayers (MLs) of InAs seed QDs are grown at 500°C, capped by y-ML GaAs at 470°C after which nanoholes are formed and used as a template for regrowth of z-ML InAs QDs at 470°C

Summary

Introduction

Xie Q, Madhukar A, Chen P, Kobayashi NP: Vertically self-organized InAs quantum box islands on GaAs(100). Heitz R, Mukhametzhanov I, Madhukar A, Hoffmann A, Bimberg D: Temperature dependent optical properties of self-organized InAs/GaAs quantum dots. Yeo I, Dong Song J, Lee J: Temperature-dependent energy band gap variation in self-organized InAs quantum dots. Polimeni A, Patane A, Henini M, Eaves L, Main PC: Temperature dependence of the optical properties of InAs/AlyGa1-yAs self-organized quantum dots. To reduce the stack number in chirped QD structures without compromising bandwidth, the QDs can be replaced by certain types of lateral quantum dot molecules (QDMs). Vertical QDMs have been a subject of intense interest since the demonstrations of QD coupling [12] and

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Conclusion