Room-temperature ultraviolet laser emission from self-assembled ZnO microcrystallite thin films

TLDR

The hexagonal facets of the ZnO microcrystallites naturally form Fabry–Pérot cavities, enabling lasing. The ZnO microcrystallites are grown by laser molecular beam epitaxy and self‑assemble into parallel arrays on sapphire substrates. Room‑temperature UV laser emission is achieved from the ZnO microcrystallite films, exhibiting excitonic optical gain an order of magnitude higher than bulk ZnO and marking a key advance toward nanometer photoelectronics.

Abstract

Room-temperature ultraviolet (UV) laser emission of ZnO microcrystallite thin films is reported. The hexagonal ZnO microcrystallites are grown by laser molecular beam epitaxy. They are self-assembled and parallelly arrayed on sapphire substrates. The facets of the hexagons form natural Fabry–Pérot lasing cavities. The optical gain for the room-temperature UV stimulated emission is of an excitonic nature and has a peak value an order of magnitude larger than that of bulk ZnO crystal. The observation of room-temperature UV lasing from the ordered, nano-sized ZnO crystals represents an important step towards the development of nanometer photoelectronics.