Open Access Nano Express

Improving the emission efficiency of MBE-grown GaN/AlN QDs by strain control

Lang Niu, Zhibiao Hao*, Jiannan Hu, Yibin Hu, Lai Wang and Yi Luo

Author Affiliations

Department of Electronic Engineering, Tsinghua National Laboratory for Information Science and Technology, Tsinghua University, Beijing 100084, People's Republic of China

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Nanoscale Research Letters 2011, 6:611  doi:10.1186/1556-276X-6-611

Published: 2 December 2011

Abstract

The quantum-confined stark effect induced by polarization has significant effects on the optical properties of nitride heterostructures. In order to improve the emission efficiency of GaN/AlN quantum dots [QDs], a novel epitaxial structure is proposed: a partially relaxed GaN layer followed by an AlN spacer layer is inserted before the growth of GaN QDs. GaN/AlN QD samples with the proposed structure are grown by molecular beam epitaxy. The results show that by choosing a proper AlN spacer thickness to control the strain in GaN QDs, the internal quantum efficiencies have been improved from 30.7% to 66.5% and from 5.8% to 13.5% for QDs emitting violet and green lights, respectively.

Keywords:
GaN QDs; quantum-confined stark effect; internal quantum efficiency