Control of the 3-Fold Symmetric Shape of Group III-Nitride Quantum Dots: Suppression of Fine-Structure Splitting

Abstract

Controlling the in-plane symmetry of wide-bandgap semiconductor quantum dots (QDs) is essential for room temperature quantum photonic applications using polarization entangled photon pairs. Herein, we report the formation of 3-fold symmetric group III-nitride QDs at the apex of a triangular pyramid via a self-limited growth mechanism. We employed the in-plane rotational symmetry of the c-plane of a Wurtzite crystal and the large built-in piezoelectric field to reduce fine-structure splitting. The QDs exhibit emission that is distinguishable from that of sidewall quantum wells, and the biexciton–exciton cascade possesses a single-photon nature. We observed the relatively low optical polarization anisotropy and small fine structure splitting under the measurement limit (270 μeV) with the 3-fold symmetric QD. In contrast with current strategies that consider group III-nitride QDs as strongly polarized single-photon emitters, our approach for controlling the QD symmetry provides a new perspective on such QDs, as polarization-entangled photon pairs.

Photoelectrochemical water-splitting using GaN pyramidal dots and their long-term stability in the two-electrode configuration

“…44 Typically, it is very difficult to observe the FX peak of GaN nanostructures, especially dots, at RT, largely because of the insufficient radiative recombination of carriers over non-radiative recombination caused by defects and surface states. 45,46 The absorption spectrum related to the FX peak was observed at 360 nm, and was blue-shifted by 5 nm because of Stocks shift. 27 Based on these structural and optical characterizations, we could carefully conclude that highly crystalline GaN PDs were successfully formed on the Si(111) substrate using the Ga pre-deposition method.…”