a Solid-state single photon sources with polarisation control operating beyond the Peltier cooling barrier of 200 K are desirable for a variety of applications in quantum technology. Using a non-polar InGaN system, we report the successful realisation of single photon emission with a g (2) (0) of 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 in semiconductor quantum dots. The temperature insensitivity of these properties, together with the simple planar epitaxial growth method and absence of complex device geometries, demonstrates that fast single photon emission with polarisation control can be achieved in solid-state quantum dots above the Peltier temperature threshold, making this system a potential candidate for future on-chip applications in integrated systems.

Nitride quantum dots are well suited for the deterministic generation of single photons at high temperatures. However, this material system faces the challenge of large in-built fields, decreasing the oscillator strength and possible emission rates considerably. One solution is to grow quantum dots on a non-polar plane; this gives the additional advantage of strongly polarized emission along one crystal direction. This is highly desirable for future device applications, as is electrical excitation. Here, we report on electroluminescence from non-polar InGaN quantum dots. The emission from one of these quantum dots is studied in detail and found to be highly polarized with a degree of polarization of 0.94. Single-photon emission is achieved under excitation with a constant current giving a g ð2Þ ð0Þ correlation value of 0.18. The quantum dot electroluminescence persists up to temperatures as high as 130 K.

We investigated the optical properties of Ge nanocrystals surrounded by Ge 3 N 4 . The broad emission ranging from infrared to blue is due to the dependence on the crystal size and preparation methods. Here, we report high resolution Photoluminescence (PL) attributed to emission from individual Ge nanocrystals (nc-Ge) spatially resolved using micro-photoluminescence and detailed using temperature and power-dependent photoluminescence studies. The measured peaks are shown to behave with excitonic characteristics and we argue that the spread of the nc-Ge peaks in the PL spectrum is due to different confinement energies arising from the variation in size of the nanocrystals.Semiconductor nanostructures are arguably the most promising technology for future optoelectronics and memory device applications due to the recent rapid advances in nanoscale science and technqiues [1][2][3] . Ge is an indirect gap semiconductor, with two main electronic transitions, the first at 0.67 eV (indirect) the second at 0.8 eV (direct) and Ge nanocrystals (nc-Ge) are one of the candidates for such applications due to their superior charge storage performance [1][2][3] . Several methods can be used to form nc-Ge such as Ge ion implantation 4 , N 2 + implantation 5 , SiGe oxidation 6 , thermal annealing of Ge thin films 7,8 , molecular beam epitaxy 9, and co-deposition of Ge with SiO 2 3,10,11 . Ge nanocrystals have been shown to emit photoluminescence (PL) covering a vast spectrum in both the visible, with wavelengths ranging from 460 nm to 515 nm and in the infrared at around 1600 nm 4,10-17 . PL previously reported for nc-Ge has been shown to give broad emission spectra in the visible range with a full width at half maximum (FWHM) of a few hundred meV. This broad spectrum indicates an ensemble effect of the nanocrystals 4,10-15 , individual nc-Ge emission has never been resolved. The origin of visible PL from nc-Ge has been discussed by Kanemitsu et al. who reported a change in the Ge crystalline structure at diameters below 4 nm, departing from the usual diamond structure. This new structure, beyond the 4 nm limit, is thought to allow for their observed visible luminescence with the character of a direct transition 11 . Contrary to Kanemitsu, Giri et al. reported observation of PL from Ge nanocrystals of a larger diameter, 4~13 nm embedded in SiO 2 4 . In addition, S. Takeoka et al. measured PL that was dependent on Ge nanocrystals with average diameters of 0.9~5.3 nm embedded in SiO 2 . The PL was found to range from the near infrared at a diameter of 5.3 nm to an energy slightly larger than the band gap of bulk Ge as the nanocrystal size decreased down to 0.9 nm 17 . The broadness of the emission can be atributed to the dependence of the PL energy on nanocrystal size, but the precise explanation of the origin of this emission remains unclear. Ensemble effects have obscured the finer details of the PL spectrum, contributing to the controversy as to the origin of the Ge nanocrystal luminescence.In this paper, Ge nanocrystals with a d...

In order to demonstrate cavity quantum electrodynamics using photonic crystal (PhC) cavities fabricated around self-assembled quantum dots (QDs), reliable spectral and spatial overlap between the cavity mode and the quantum dot is required. We present a method for using photoresist to optically fabricate heterostructure cavities in a PhC waveguide with a combined photolithography and micro-photoluminescence spectroscopy system. The system can identify single QDs with a spatial precision of ±25 nm, and we confirm the creation of high quality factor cavity modes deterministically placed with the same spatial precision. This method offers a promising route towards bright, on-chip single photon sources for quantum information applications.