Carrier dynamics in site- and structure-controlled InGaN/GaN quantum dots

Abstract

We report on the carrier dynamics in InGaN/GaN dot-in-nanowire quantum dots revealed by systematic mapping between optical properties and structural parameters of the quantum dots. Such a study is made possible by using quantum dots with precisely controlled locations and sizes. We show that the carrier dynamics is governed by two competing mechanisms: 1) excitons are protected from surface recombination by a potential barrier formed due to strain-relaxation at the sidewall surface; 2) excitons can overcome the potential barrier by tunnelling and thermal activation. This carrier dynamics model successfully explains the following surprising experimental findings on individual quantum dots. Firstly, there exist strong statistical correlations among multiple optical properties of many individual quantum dots, despite variations of these properties resulting from inevitable structural variations among the quantum dots. Secondly, the antibunching property of quantum dot emission exhibits abnormal ladle-shaped dependence on the decay time and temperature. Our results can guide the way toward nitride-based high temperature singlephoton emitters and nano-photonic devices.

Sub-μeVdecoherence-induced population pulsation resonances in an InGaN system

“…Within each nanowire, the tapered design can give additional inhomogeneous broadening because the energies of transitions within the DINWs along the tapered end are heavily af-fected by the DINW diameter. Generally, transitions for smaller diameter DINWs are blue-shifted compared to larger diameter DINWs due to strain relief effects [19]. The sample photoluminescence (PL) is shown in the inset of Fig.…”

Measurement of the Emission Lifetime of a GaN Interface Fluctuation Quantum Dot by Power Dependent Single Photon Dynamics

“…However, III‐Nitrides have limitations because they suffer from a spectral diffusion induced linewidth broadening (which can result in emission linewidths of a few meV) . This spectral diffusion occurs due to an interaction between the internal‐field induced exciton permanent dipole moment and the fluctuating electric field of charges trapped in relatively large densities of surrounding defects . Recently, interface fluctuation GaN QDs have been successfully fabricated, which exhibit narrow emission linewidths and ultra‐clean single photon emission …”

Emission of Linearly Polarized Single Photons from Quantum Dots Contained in Nonpolar, Semipolar, and Polar Sections of Pencil-Like InGaN/GaN Nanowires

“…Indeed single photon emission has already been demonstrated over range of 280 -620 nm using III-nitride quantum dots (QDs) of different material composition. [2][3][4][5][6][7][8][9][10][11][12][13][14][15] In addition, the benefits of high band offsets in III-nitride heterostructures have been exploited for strong exciton confinement, thus allowing single photon operation at room temperature 8,9 and even in hot environments (77 ˚C). 13 In other advances, a certain degree of single photon polarization control has been achieved via manipulation of the emitting QD shape, 6,12 and electrically excited single photon emission has also been reported for both columnar and bulk device morphologies.…”