Comprehensive Electro-Optical Investigation of a Ga-Doped AlN Nanowire LED for Applications in the UV-C Range

Abstract

With the aim of targeting sanitization applications, the realization of a 285 nm AlN nanowire-based light-emitting diode is reported, with a focus on the comprehensive study of its electro-optical properties. The active region consists of AlGaN, with a Ga content of at most 1%, as measured by energy-dispersive X-ray spectroscopy. Optical properties were investigated by means of cathodo-(CL) and photoluminescence. They reveal a high degree of localization of electron−hole pairs on recombination centers behaving as quantum dots. The AlN pn-junctions show diode-like rectifying behavior with 5 orders of magnitude difference between ±10 V. The main factor limiting the current at larger forward bias is found to be tunnellimited injection obeying a Fowler−Nordheim model. Spatially resolved CL and electron beam−induced current measurements demonstrate that the active region overlaps the space charge region. Finally, electroluminescence (EL) spectroscopy was performed. This methodology allowed us to identify current limitations, the main one being injection efficiency, opening the path to efficiency improvement solutions.