Open Access Nano Express

Optical properties of as-grown and annealed InAs quantum dots on InGaAs cross-hatch patterns

Chalermchai Himwas, Somsak Panyakeow and Songphol Kanjanachuchai*

Author Affiliations

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

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Nanoscale Research Letters 2011, 6:496  doi:10.1186/1556-276X-6-496

Published: 17 August 2011

Abstract

InAs quantum dots (QDs) grown on InGaAs cross-hatch pattern (CHP) by molecular beam epitaxy are characterized by photoluminescence (PL) at 20 K. In contrast to QDs grown on flat GaAs substrates, those grown on CHPs exhibit rich optical features which comprise as many as five ground-state emissions from [1-10]- and [110]-aligned QDs, two wetting layers (WLs), and the CHP. When subject to in situ annealing at 700°C, the PL signals rapidly degrades due to the deterioration of the CHP which sets the upper limit of overgrowth temperature. Ex situ hydrogen annealing at a much lower temperature of 350°C, however, results in an overall PL intensity increase with a significant narrowing and a small blueshift of the high-energy WL emission due to hydrogen bonding which neutralizes defects and relieves associated strains.

Keywords:
quantum dots; cross-hatch patterns; photoluminescence; annealing; InAs; InGaAs.