Electron-Beam-Pumped UVC Emitters Based on an (Al,Ga)N Material System

Powerful emitters of ultraviolet C (UVC) light in the wavelength range of 230-280 nm are necessary for the development of effective and safe optical disinfection technologies, highly sensitive optical spectroscopy and non-line-of-sight optical communication. This review considers UVC emitters with electron-beam pumping of heterostructures with quantum wells in an (Al,Ga)N material system. The important advantages of these emitters are the absence of the critical problem of p-type doping and the possibility of achieving record (up to several tens of watts for peak values) output optical power values in the UVC range. The review consistently considers about a decade of world experience in the implementation of various UV emitters with various types of thermionic, field-emission, and plasma-cathode electron guns (sources) used to excite various designs of active (light-emitting) regions in heterostructures with quantum wells of AlxGa1-xN/AlyGa1-yN (x = 0-0.5, y = 0.6-1), fabricated either by metal-organic chemical vapor deposition or by plasma-activated molecular beam epitaxy. Special attention is paid to the production of heterostructures with multiple quantum wells/two-dimensional (2D) quantum disks of GaN/AlN with a monolayer's (1 ML similar to 0.25 nm) thickness, which ensures a high internal quantum efficiency of radiative recombination in the UVC range, low elastic stresses in heterostructures, and high-output UVC-optical powers.

Automated summary

This review focuses on UVC emitters with electron-beam pumping of heterostructures with quantum wells in an (Al,Ga)N material system. The advantages of these emitters include the absence of p-type doping and the ability to achieve high-output optical power values in the UVC range. The review discusses the world experience in implementing various UV emitters and pays special attention to the production of heterostructures with multiple quantum wells/two-dimensional quantum disks of GaN/AlN.