The nonlinear ~third to fourth order! as well as linear photoconductivity in a Gallium nitride/ Indium-Gallium nitride ~GaN/InGaN! heterostructure is investigated using femtosecond pulses in the infrared ~IR! and near ultraviolet ~UV!. An anomalous IR photoresponse is explained by a four level model for the GaN region including defect density fluctuations and nonlinear carrier transport phenome...

Efficiency droop is a major obstacle facing high-power application of InGaN/GaN quantum-well (QW) light-emitting diodes (LEDs). In this paper, we report the suppression of efficiency droop induced by the process of density-activated defect recombination in nanorod structures of a-plane InGaN/GaN QWs. In the high carrier density regime, the retained emission efficiency in a dry-etched nanorod sa...

Cavity-enhanced single-photon emission in the blue spectral region was measured from single InGaN/GaN quantum dots. The low-Q microcavities used were characterized using micro-reflectance spectroscopy where the source was the enhanced blue output from a photonic crystal fibre. Micro-photoluminescence was observed from several cavities and found to be ~10 times stronger than typical InGaN quantu...

This Letter investigates the efficiency enhancement achieved by tunnel junction insertion into the InGaN/GaN multi-quantum well (MQW) active region of blue light emitting diodes (LEDs). The peak quantum efficiency of such LED exceeds 100%, but the maximum wall-plug efficiency (WPE) hardly changes. However, due to the increased bias, the WPE peaks at much higher input power, i.e., the WPE droop ...

We investigate the effects of reduced exciton diffusion on the emission properties in InGaN/GaN multiple-quantum-well nanorods. Time-resolved photoluminescence spectra are recorded and compared in dry-etched InGaN/GaN nanorods and parent multiple quantum wells at various temperatures with carrier density in different regimes. Faster carrier recombination and absence of delayed rise in the emiss...

Reduction of the intensity noise in semiconductor lasers is important subject to extend application range of the device. Blue-violet InGaN laser reveals high quantum noise when the laser is operated with low output power. The authors proposed a new scheme of noise reduction both for the optical feedback noise and the quantum noise by applying electric feedback which is positive type at a high f...

We investigated the origin of broad luminescence observed from an array of site-controlled InGaN nanodots grown by selective area epitaxy (SAE). Epitaxially grown site-controlled nanodots with lateral dimensions <50 nm and an array density of 10 cm 2 have been studied. During the nanoscale SAE, incorporation of adatoms from the SiO2 mask has greater relative importance, resulting in a non-unifo...

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The growth of high-quality thick InN films is challenging because of the lack of native substrates. In this work, we demonstrate the use of a linearly graded InGaN buffer layer for the growth of InN films on GaN substrates. A 500nm InN film with <0.1 nm RMS roughness is obtained with a peak mobility of 1410 cm2/(V&s) at 300K. A strong room temperature photoluminescence showing a bandgap of 0.65...

Three series of samples with different NH3 flow rate are grown and the optical and structural properties are investigated. It is found that apart from a positive effect on keeping a high partial pressure of nitrogen to enhance indium incorporation, NH3 may also play a negative effect on indium incorporation during InGaN growth. Especially, when temperature is relatively high, the hydrogen gener...