Non-polar InGaN quantum dot emission with crystal-axis oriented linear polarization

Abstract

Polarization sensitive photoluminescence is performed on single non-polar InGaN quantum dots. The studied InGaN quantum dots are found to have linearly polarized emission with a common polarization direction defined by the [0001] crystal axis. Around half of ∼ 40 studied dots have a polarization degree of 1. For those lines with a polarization degree less than 1, we can resolve fine structure splittings between −800 µeV and +800 µeV, with no clear correlation between fine structure splitting and emission energy.

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

“…All calculations were performed on a 50 × 50 × 30-nm 3 supercell with periodic boundary conditions. With these assumptions, the calculated ground state transition energies were in the range of 2.7 to 2.9 eV, close to typical experimental values [27,32,33,[41][42][43][44] and those discussed below. Therefore, the chosen geometries and indium contents should give a reasonable description of the structures considered here.…”

“…Furthermore, while the DOLPs of a-plane quantum wells (QWs) are limited to ~0.60 [26], we report a much higher average DOLP of ~0.90 in a-plane InGaN QDs. Previous investigations have reported polarization properties of some a-plane InGaN QDs along [0001] [27], orthogonal to those reported in a-plane QWs (along ) [26,28,29]. We find that this is a special case to the general behavior of a-plane QDs.…”

“…The a-plane sample surface exhibits striated features along the c-axis [31], further demonstrating the orthogonality between the polarization axis and the crystal c-direction. As such, the PL polarized parallel to the c-axis should correspond to the weaker polarized component of QD emission, instead of the stronger one as previously reported [27].…”

“…In addition to strong shape anisotropies, alloy fluctuation effects might also contribute to the observed behavior [47]. As such, the previous report [27] is an investigation of these 9% QDs, which is a special case to the general behavior of a-plane InGaN QDs. It is also worth noting that the DOLPs of such QDs are similarly high and follow the same distribution as that shown in Figure 4A.…”

Wafer-scale Fabrication of Non-Polar Mesoporous GaN Distributed Bragg Reflectors via Electrochemical Porosification

“…Non-polar III-nitride materials promise not only the advantage of reduced internal electric fields and thus higher rates of radiative recombination for improved device efficiencies, but also additional unique properties such as the emission of strongly linearly polarised light due to the presence of anisotropic biaxial strain in the asymmetric non-polar crystal. A high degree of polarisation has been achieved not only in the emission from non-polar quantum wells, with potentially wide-ranging application in displays1112, but also in single non-polar quantum dots, whose polarised emission could be utilised in quantum key distribution protocols13. In both these applications, non-polar DBRs could be used to improve light extraction, increasing device efficiency, with the development of micro-pillar cavities providing a potential route to light-matter coupling in the quantum dot case.…”