Surface Emitting, High Efficiency Near-Vacuum Ultraviolet Light Source with Aluminum Nitride Nanowires Monolithically Grown on Silicon

To date, it has remained challenging to realize electrically injected light sources in the vacuum ultraviolet wavelength range (similar to 200 nm or shorter), which are important for a broad range of applications, including sensing, surface treatment, and photochemical analysis. In this Letter, we have demonstrated such a light source with molecular beam epitaxially grown aluminum nitride (AIN) nanowires on low cost, large area Si substrate. Detailed angle dependent electroluminescence studies suggest that, albeit the light is TM polarized, the dominant light emission direction is from the nanowire top surface, that is, along the c axis, due to the strong light scattering effect. Such an efficient surface emitting device was not previously possible using conventional c-plane AIN planar structures. The AIN nanowire LEDs exhibit an extremely large electrical efficiency (>85%), which is nearly ten times higher than the previously reported AIN planar devices. Our detailed studies further suggest that the performance of AIN nanowire LEDs is predominantly limited by electron overflow. This study provides important insight on the fundamental emission characteristics of AIN nanowire LEDs and also offers a viable path emitting near-vacuum ultraviolet light source through direct electrical injection. to realize an efficient surface emitting near-vacuum ultraviolet light source through direct electrical injection.