In this work, we demonstrate high-performance electrically injected GaN/InGaN core-shell nanowire-based LEDs grown using selective-area epitaxy and characterize their electro-optical properties. To assess the quality of the quantum wells, we measure the internal quantum efficiency (IQE) using conventional low temperature/room temperature integrated photoluminescence. The quantum wells show a peak IQE of 62%, which is among the highest reported values for nanostructure-based LEDs. Time-resolved photoluminescence (TRPL) is also used to study the carrier dynamics and response times of the LEDs. TRPL measurements yield carrier lifetimes in the range of 1–2 ns at high excitation powers. To examine the electrical performance of the LEDs, current density–voltage (J-V) and light-current density-voltage (L-J-V) characteristics are measured. We also estimate the peak external quantum efficiency (EQE) to be 8.3% from a single side of the chip with no packaging. The LEDs have a turn-on voltage of 2.9 V and low series resistance. Based on FDTD simulations, the LEDs exhibit a relatively directional far-field emission pattern in the range of 15°. This work demonstrates that it is feasible for electrically injected nanowire-based LEDs to achieve the performance levels needed for a variety of optical device applications.

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The exceptional material properties of Lithium Niobate (LiNbO3) make it an excellent material platform for a wide range of RF, MEMS, phononic and photonic applications; however, nano-micro scale device concepts require high fidelity processing of LN films. Here, we reported a highly optimized processing methodology that achieves a deep etch with nearly vertical and smooth sidewalls. We demonstrated that Ti/Al/Cr stack works perfectly as a hard mask material during long plasma dry etching, where periodically pausing the etching and chemical cleaning between cycles were leveraged to avoid thermal effects and byproduct redeposition. To improve mask quality on X- and Y-cut substrates, a H2-plasma treatment was implemented to relieve surface tension by modifying the top surface atoms. Structures with etch depths as deep as 3.4 µm were obtained in our process across a range of crystallographic orientations with a smooth sidewall and perfect verticality on several crystallographic facets.