III‐Nitride semiconductor‐based quantum dots (QDs) play an essential role in solid‐state quantum light sources because of their potential for room‐temperature operation. However, undesired background emission from the surroundings deteriorates single‐photon purity. Moreover, spectral diffusion causes inhomogeneous broadening and limits the applications of QDs in quantum photonic technologies. To overcome these obstacles, it is demonstrated that directly pumping carriers to the excited state of the QD reduces the number of carriers generated in the vicinities. The polarization‐controlled quasi‐resonant excitation is applied to InGaN QDs embedded in GaN nanowire. To analyze the different excitation mechanisms, polarization‐resolved absorptions are investigated under the above‐barrier bandgap, below‐barrier bandgap, and quasi‐resonant excitation conditions. By employing polarization‐controlled quasi‐resonant excitation, the linewidth is reduced from 353 to 272 µeV, and the second‐order correlation value is improved from 0.470 to 0.231. Therefore, a greater single‐photon purity can be obtained at higher temperatures due to decreased linewidth and background emission.
We present the first monolithic fabrication of a-IGZO TFTs on a GaN-based micro-LED array at a low temperature to overcome the weak thermal endurance constraint of the organic planarization layer for high resolution and stable low-cost LED displays.
For decades, group‐III‐nitride‐based light‐emitting diodes (LEDs) have been regarded as a light emitting source for future displays by virtue of their novel properties such as high efficiency, brightness, and stability. Nevertheless, realization of high pixel density displays is still challenging due to limitations of pixelation methods. Here, a maskless and etching‐free micro‐LED (µLED) pixelation method is developed via tailored He focused ion beam (FIB) irradiation technique, and electrically driven sub‐micrometer‐scale µLED pixel arrays are demonstrated. It is confirmed that optical quenching and electrical isolation effects are simultaneously induced at a certain ion dose (≈1014 ions cm−2) without surface damage. Furthermore, highly efficient µLED pixel arrays at sub‐micrometer scale (square pixel, 0.5 µm side length) are fabricated. Their pixelation and brightness are verified by various optical measurements such as cathodo‐, photo‐, and electroluminescence. It is expected that the FIB‐induced optical quenching and electrical isolation method can pioneer a new defect engineering technology not only for µLED fabrication, but also for sub‐micrometer‐scale optoelectronic devices.
Bell’s palsy is an acute peripheral facial paralysis with no detectable cause. Although the prognosis of Bell’s palsy is generally good, some patients experience poor recoveries and there is no established treatment for those that do not recover even after receiving the conventional treatment. Here we present two cases of refractory Bell’s palsy with facial nerve enhancement in magnetic resonance imaging who showed symptomatic improvement after the late administration of high-dose intravenous methylprednisolone.
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