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We demonstrated a full visible spectrum emission from a 3D multifacet microrod light-emitting diode (LED). The microrods were fabricated by top-down patterned etched and regrowth. Hexagonal {11-20} and {11-22} facets were first formed on the microrods, then gradually transformed to {10-10} and {10-11} facets. This facet evolution was attributed to the growth competition among different crystal planes. The multiple quantum wells grown on the microrods also followed this facet evolution and resulted in broad emission spectrum. The device can have direct white light emission covering full visible spectral range from 460 to 660 nm under electrical injection.

We report the fabrication and study of coreshell InGaN/GaN multiple quantum well (MQW) nanorod photovoltaic device. The nanorods were fabricated from a GaN substrate by top-down etch, followed by InGaN/GaN MQW growth. The 3D geometry allows higher Indium incorporation and extends the solar absorption spectral range as compared with a planar reference sample. The proof-of-concept coreshell nanorod photovoltaic device has a fill factor of about 54.2%, the short current density of 1.16 mA/cm2, the open circuit voltage of 0.68 V, and the power conversion efficiency of 0.38%, respectively.

We report the study of InGaN/GaN multiple quantum wells (MQWs) grown on multi-facet microrods. The multi-facet MQWs have broad emission spectrum. Electrical injection was demonstrated with emission color ranged from red to blue.

The radiative and non-radiative lifetime of high In content nanopyramid GaN LEDs are investigated by time resolved and temperature dependent photoluminescent measurement. The radiative recombination efficiency is much improved compared with the conventional c-plane LED.

We report the growth temperature effect on the crystalline and optical properties of (1122) semipolar GaN and InGaN/GaN MQWs. It shows that a lower growth temperature at 1020 °C produces better crystalline and optical properties.

We report the study of an electrically driven nanopyramid-on-pillar green light-emitting diode (LED). The pyramid-on-pillar nanostructure was fabricated by top-down etching from a GaN template, followed by epitaxial regrowth. High-In-content InGaN/GaN multiple quantum wells (MQWs) were grown on semipolar pyramid and nonpolar pillar surfaces. The measured radiative lifetimes of MQWs on these two surfaces were 2 orders of magnitude shorter than that of a conventional c-plane (0001) MQW owing to their lower polarization field. Electrical injection performance was also demonstrated and discussed.

Fiber-to-the-antenna (FTTA) system can be a cost-effective technique for distributing high frequency signals from the head-end office to a number of remote antenna units via passive optical splitter and propagating through low-loss and low-cost optical fibers. Here, we experimentally demonstrate an optical ultra-wideband (UWB) - impulse radio (IR) FTTA system for in-building and in-home applications. The optical UWB-IR wireless link is operated in the W-band (75 GHz - 110 GHz) using our developed near-ballistic unitraveling-carrier photodiode based photonic transmitter (PT) and a 10 GHz mode-locked laser. 2.5 Gb/s UWB-IR FTTA systems with 1,024 high split-ratio and transmission over 300 m optical fiber are demonstrated using direct PT modulation.