UV-A laser structures are designed and grown on AlGaN and GaN templates using molecular beam epitaxy. Devices fabricated from these structures are characterized to evaluate their electrical and optical properties. Additionally, a two-step process integrating dry and wet etching techniques has been successfully implemented, resulting in the attainment of smooth and vertically aligned facets within the AlGaN/GaN structures.

The traditional plasma etching process for defining micro-LED pixels could lead to significant sidewall damage. Defects near sidewall regions act as non-radiative recombination centers and paths for current leakage, significantly deteriorating device performance. In this study, we demonstrated a novel selective thermal oxidation (STO) method that allowed pixel definition without undergoing plasma damage. The 10-µm green micro-LED array fabricated exhibited leakage currents density 1.2×10−6 A/cm² at −10 V and a peak on-wafer external quantum efficiency of approximately 6.55%.

This work reviews recent studies describing degradation phenomena in UV-C LEDs, including the effect of charged defects causing variation in injection efficiency, de-hydrogenation of vacancies, magnesium compensation, and the use of numerical simulations to confirm the degradation models.