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HL: Fachverband Halbleiterphysik

HL 10: Focus Session: Highlights of Materials Science and Applied Physics I (joint session DS/HL)

HL 10.3: Topical Talk

Dienstag, 28. September 2021, 14:30–15:00, H3

Monolayer-thick GaN/AlN heterostructures for UVB & UVC ranges: technology, design and properties — Valentin Jmerik, Alexey Toropov, Valery Davydov, and •Sergey Ivanov — Ioffe Institute, Polytekhnicheskaya 26, Saint Petersburg, 194921, Russia

The development of monolayer (ML)-thick GaN/AlN multilayer heterostructures for deep ultraviolet (UV) optoelectronics is discussed. Analysis of plasma-assisted molecular beam epitaxy and metal-organic vapor phase epitaxy show that extreme interface sharpness and sub-ML accuracy in controlling the layer thickness are the main advantages of the former, while the lowest density of threading dislocations and wide possibilities for the implementation of various two-dimensional growth mechanisms are the attractive features of the latter. The structural properties of ML GaN/AlN heterostructures are evaluated comparatively by X-ray diffraction, scanning transmission electron microscopy and Raman spectroscopy. Studies of the optical properties of ML-thick GaN/AlN quantum wells (QWs) reveal that quenching of the Stark effect, suppression of polarization switching, as well as a true excitonic nature of the UV-emission in ultra-thin (1-2ML) QWs ensure a high internal quantum yield of 75% in such structures emitting at 235 nm. High optical quality of 100-nm-thick layers of ML-GaN/AlN digital alloys is confirmed by the optically pumped stimulated emissions in the range 262-290 nm with a minimum threshold of 700kW/cm2. The possibilities of using ML-GaN/AlN MQWs to fabricate powerful (Watt-range) electron-beam pumped UVC-emitters in the spectral range 240-260 nm are demonstrated.