Single-dislocation ultraviolet light emission

Abstract

Micro-nano ultraviolet light sources have recently attracted great attention due to their promising applications in future quantum display, photoelectric detection sensors, biomedical devices, and so on. Design of ultraviolet light sources with smaller size, stronger emission intensity, and higher integration, are the key aspects for the development of high-performance micro-nano ultraviolet devices. Here, we demonstrate that unidirectional threading dislocation arrays in an AlN thin film can emit ultraviolet light with wavelength of ∼ 317 nm. The density of AlN dislocations is ∼ 4 × 1010 cm−2, and the light emission intensity of AlN dislocations is comparable to the intrinsic emission of the AlN thin film. By combining aberration-corrected transmission electron microscopy, atomic-resolution valence electron energy-loss spectroscopy, and first-principles calculations, the atomic and electronic structures and the band gaps of the AlN threading dislocations are determined. It is found that the AlN threading dislocations are comprised of edge, screw, and mixed dislocations. All the AlN dislocations exhibit smaller band gaps compared to the AlN bulk due to the increase of the Al-N bond length at the dislocation cores. The dangling bonds of Al and N at the edge dislocations, Al-Al and NN bonds at the screw dislocations cause the defect states in the band gaps. This study not only has clarified the atomic origin of dislocation nano-optics, but also will encourage the development of microelectronics and optoelectronic devices based on dislocation ultraviolet light emission.