High-Performance Ultraviolet Light-Emitting Diodes Using n-ZnO/p-hBN/p-GaN Contact Heterojunctions.

Effective ultraviolet light-emitting diodes (LEDs) were fabricated by clamping the n-ZnO films on the top of p-hBN/p-GaN/sapphire substrates. An ultraviolet emission originating from ZnO was measured from the diode under a forward bias, the electroluminescence (EL) spectra of which show a peak wavelength of ∼376 nm with a narrow full-width at half maximum of ∼12 nm. Compared with the reference diode fabricated by directly growing n-ZnO on the p-hBN substrates using metal-organic chemical vapor deposition, the proposed diode showed a dramatic increment of the EL intensity; meanwhile, its emission onset lowered down considerably. The improved optical property of the proposed LED is mainly ascribed to suppressing the formation of the BNO-related layer at the n-ZnO/p-hBN interface. The present work provides a simple and feasible approach for developing advanced ZnO-based optoelectronic devices.