High-Quality AlN for UV-LEDs Fabricated via Ion Implantation

Abstract

AlN materials are widely used in optoelectronic, power electronic, and radio frequency applications. However, the significant lattice and thermal mismatch between heteroepitaxial AlN and its substrate leads to a high threading dislocations (TDs) density, which degrades the performance of device. In this work，we introduces a novel, cost-effective, and stable approach for the epitaxial growth of AlN. We injects different doses of nitrogen ions into nano patterned sapphire substrates, followed by the deposition of an AlN layer using metal-organic chemical vapor deposition. Ultraviolet light-emitting diodes (UV-LEDs) with a luminescence wavelength of 395 nm were fabricated on it, and the optoelectronic properties were evaluated. Compared with the sample prepared by traditional method, the screw TDs density of the sample injected with N ions at a dose of 1×10¹³ cm^-2 decreased by 82%, while having the lowest roughness and a 52% increase in photoluminescence intensity. It can be seen that appropriate doses of N ion implantation can promote the lateral growth and merging process in AlN heteroepitaxy. This is due to the process of implantation of N ions can suppress the tilt and twist of the nucleation islands, effectively reducing the density of TDs in AlN. Furthermore, in comparison to the control LED, the light output power and wall plug efficiency of the LED prepared on the high quality AlN template increased by 63.8% and 61.7%, respectively. The observed enhancement in device performance is attributed to the decreased TDs density of the epitaxial layer, which effectively reduces the nonradiative recombination centers. In summary, this study suggests that ion implantation can significantly improve the quality of epitaxial AlN, thereby facilitating the development of high-performance AlN-based UV-LEDs.