M-plane AlGaN digital alloy for microwire UV-B LEDs

The growth of non-polar AlGaN digital alloy (DA) is achieved by metal-organic vapor phase epitaxy using GaN microwire m-facets as the template. This AlGaN DA consisting of five periods of two monolayer-thick layers of GaN and AlGaN (approximately 50% Al-content) is integrated into the middle of an n-p GaN/AlGaN junction to design core-shell wire-μLED. The optical emission of the active zone investigated by 5 K cathodoluminescence is consistent with the AlGaN bulk alloy behavior. Several contributions from 295 to 310 nm are attributed to the lesser thickness and/or composition fluctuations of AlGaN DA. Single-wire μLED is fabricated using a lithography process, and I–V measurements confirm a diode rectifying behavior. Room temperature UV electroluminescence originating from m-plane AlGaN DA is accomplished at 310 nm.