Two-photon excitation spectroscopy of coupled asymmetric GaN/AlGaN quantum discs

This is the authors' abstract. We don't add key points for this paper.

By using two-photon excitation spectroscopy we take advantage of the increased spatial resolution to perform time-integrated and time-resolved photoluminescence measurements on several discrete stacks of GaN quantum discs. The stack structure consisted of coupled asymmetric GaN quantum discs with embedded AlGaN barriers, which were grown at the tip of a GaN nanocolumn. We observed that with increasing optical excitation power the carrier lifetime decreased due to free-carrier screening, with an enhancement of the screening effect in the larger quantum disc due to carrier tunnelling from the smaller quantum disc.