JMR Focus Issue on Ultra-wide Bandgap Materials, Devices and Systems, freely accessible until May 26, 2022

Ultrawide-bandgap Materials, Devices and Systems

Ultrawide-bandgap (UWBG) semiconductor technology is presently going through a renaissance, with advances in material-level understanding, extensions of known concepts to new materials, novel device concepts, and new applications all merging simultaneously. This JMR Focus Issue presents a timely selection of papers spanning the current state of the art in UWBG materials and applications, including both experimental results and theoretical developments. It covers broad research subtopics on UWBG bulk crystals and substrate technologies, UWBG defect science and doping, UWBG epitaxy, UWBG electronic and optoelectronic properties, and UWBG power devices and emitters.

UWBG semiconductors, with bandgap energies much wider than the 3.4 eV of GaN or 3.2 eV or SiC, represent an emerging new area of intensive research covering a wide spectrum that spans materials, physics, devices, and applications. As the critical electric field of dielectric breakdown increases superlinearly with the bandgap energy, UWBG semiconductors can tolerate high fields to enable high-power electronic devices for telecommunications, motor drive, power grid, electric vehicles, industrial and locomotive traction control, and various other applications. In addition, light emission from UWBG materials occurs in the deep ultraviolet (UV) part of the electromagnetic spectrum, which is attractive for extending the working wavelengths of photonic devices into the UV–visible (UV-Vis) spectra to enable potential applications in deep-UV optoelectronics, quantum information science, and bio-chemical sensing. This new class of semiconductors is also being explored for device applications in harsh environments by taking advantage of their thermal stability and radiation hardness. Compared to the development of GaN and SiC, all UWBG materials are relatively immature and still at a nascent stage. Most research efforts in UWBG focus on aluminum gallium nitride alloys (AlxGa1–xN), diamond, boron nitride (BN), and a large family of binary (typified by β-phase gallium oxide (β-Ga2O3)) and ternary oxide semiconductors. The extensive research activities on these materials is motivated by their reliable dopability and high carrier mobilities, the availability of substrates for thin-film growth, and successful demonstrations of devices.

This JMR Focus Issue provides a glimpse of the recent advancements in UWBG materials, physics, and related technologies. Despite being in its early years, tremendous progress has been made in this research field exploiting the fascinating properties of UWBG semiconductors. Fundamental materials-level work in (AlxGa1–x)N, diamond, β-Ga2O3, and other emerging UWBG materials have begun to produce device results commensurate with the fundamental advantages that these materials promise. Open questions remain in UWBG semiconductor research while new ones continuously evolve, to which first-principles computation techniques working in tandem with experimental studies have proven indispensable for improving device performance, discovering new materials with targeted functionalities, and stimulating new research directions in UWBG semiconductors.

The Focus Issue is freely accessible through May 26, 2022. You may also want to watch a this webinar, held in March, featuring authors from the issue.