arXiv subjects

Tim J. Puchtler

Publications and source records attributed to Tim J. Puchtler.

4 recordsLinked to original sources

arXiv2019

Reduction of radiative lifetime and slow-timescale spectral diffusion in InGaN polarized single-photon sources

Non-polar (11-20) a-plane quantum dots (QDs) are strong candidates for both > 200 K on-chip ultrafast polarized single-photon generation and the investigation of high temperature semiconductor QD photophysics. In this work, we report progress in the growth of a-plane InGaN QDs with a quasi-two-temperature method, which produces smooth epilayers and significantly reduced carrier trapping sites in the proximity of the QDs. Optical characterization has confirmed the ability of such QDs to emit polarized single photons and we have recorded a ~ 45% shorter average radiative lifetime and 65% reduction in the slow-timescale spectral diffusion compared to previous QDs. This growth method is an important development of the non-polar a-plane InGaN platform, opening up more possibilities in single-photon, lasing, and fundamental investigations.

cond-mat.mes-hall↗

arXiv2016

Experimental and theoretical analyses of strongly polarized photon emission from non-polar InGaN quantum dots

We present a comprehensive investigation of the polarization properties of non-polar a-plane InGaN quantum dots (QDs) and their origin with statistically significant experimental data and rigorous k.p modelling. The unbiased selection and study of 180 individual QDs allow us to compute an average polarization degree of 0.90, with a standard deviation of only 0.08. When coupled with theoretical insights, we show that a-plane InGaN QDs are highly insensitive to size differences, shape anisotropies, and indium content fluctuations. Furthermore, 91% of the studied QDs exhibit a polarization axis along the crystal [1-100] axis, with the other 9% polarized orthogonal to this direction. When coupled with their ability to emit single-photons, a-plane QDs are good candidates for the generation of linearly polarized single-photons, a feature attractive for quantum cryptography protocols.

cond-mat.mes-hall↗

arXiv2016

An ultrafast polarised single photon source at 220 K

A crucial requirement for the realisation of efficient and scalable on-chip quantum communication is an ultrafast polarised single photon source operating beyond the Peltier cooling barrier of 200 K. While a few systems based on different materials and device structures have achieved single photon generation above this threshold, there has been no report of single quantum emitters with deterministic polarisation properties at the same high temperature conditions. Here, we report the first device to simultaneously achieve single photon emission with a g(2)(0) of only 0.21, a high polarisation degree of 0.80, a fixed polarisation axis determined by the underlying crystallography, and a GHz repetition rate with a radiative lifetime of 357 ps at 220 K. The temperature insensitivity of these properties, together with the simple planar growth method, and absence of complex device geometries, makes this system an excellent candidate for on-chip applications in integrated systems.

cond-mat.mes-hall↗

arXiv2016

Ultrafast, polarized, single-photon emission from m-plane InGaN Quantum Dots on GaN nanowires

We demonstrate single photon emission from self-assembled m-plane InGaN quantum dots (QDs) embedded on the side-walls of GaN nanowires. A combination of electron microscopy, cathodoluminescence, time-resolved micro-PL and photon autocorrelation experiments give a thorough evaluation of the QDs structural and optical properties. The QD exhibits anti-bunched emission up to 100 K, with a measured autocorrelation function of g^2(0) = 0.28 (0.03) at 5 K. Studies on a statistically significant number of QDs show that these m-plane QDs exhibit very fast radiative lifetimes (260 +/- 55 ps) suggesting smaller internal fields than any of the previously reported c-plane and a-plane QDs. Moreover, the observed single photons are almost completely linearly polarized aligned perpendicular to the crystallographic c-axis with a degree of linear polarization of 0.84 +/- 0.12. Such InGaN QDs incorporated in a nanowire system meet many of the requirements for implementation into quantum information systems and could potentially open the door to wholly new device concepts.

cond-mat.mes-hall↗