Comparison between InP-based quantum dot lasers with and without tunnel injection quantum well and the impact of rapid thermal annealing

Abstract

An InP based tunnel injection quantum dot (QD) laser and a reference quantum dot laser designed to emit at 1.55 μm were grown by molecular beam epitaxy. The lattice matched tunnel injection (TI) structures consist of an InGaAs quantum well (QW), an InAlGaAs barrier and multiple InAs quantum dot layers. Quantum well and quantum dot test structures as well as the actual laser structures were treated with rapid thermal annealing (RTA) at varying temperatures (680–780 °C). Photoluminescence measurements were performed at 10 K on all samples and a strong effect of this annealing process on the emission properties is observed. The laser structures were processed into broad area lasers. Power-current characteristics were measured and evaluated. A strong improvement in device performance is observed after annealing for QD lasers while for TI-QD lasers no significant improvement was obtained, which might be caused by detuning of band energy alignment and different impact of the RTA process on the material quality of QW and QD layers.