Effects of rapid thermal annealing on the energy levels of InAs/InP self-assembled quantum dots

Abstract

We have studied the effects of thermal annealing on the electrical properties of InAs/1nP self-assembled quantum dots (QDs) using deep level transient spectroscopy (DLTS). It was found from the DLTS measurements that the activation energy of the QD signal varied from 0.47 to 0.60 eV and the emission cross section changed from 1.01 X 10(-15) to 9.63 x 10(-14) cm(2) when the annealing temperature increased up to 700degreesC. As a result of the thermal annealing process at the temperature ranging from 500 to 600degreesC, the higher activation energy and the larger emission cross section of the QD related signal were observed for the annealed samples compared to those for the as-grown sample. On the basis of the capture barrier height for the QDs structure being lowered from 0.24 to 0.06 eV at the annealing temperature of 700degreesC, thermal damage was considered as the reason. The appropriate annealing process can provide a clue for the engineering of the energy levels in the self-assembled QD structures. (C) 2004 Elsevier B.V. All rights reserved.