Challenges, Power-Device Progress, and Emerging Harsh-Environment Applications for Ultrawide-Bandgap Diamond Semiconductors

Diamond has emerged as a promising ultrawide-bandgap semiconductor material for next-generation electronics because of its unique combination of a wide bandgap, high critical electric field, superior carrier transport properties, exceptionally high thermal conductivity, and strong chemical and radiation stability. Over the past two decades, progress in crystal growth, substrate engineering, surface control, dielectric integration, and device fabrication has advanced diamond electronics beyond early proof-of-concept demonstrations. The review connects material properties, growth, doping, defects, and figures of merit with reported performance in hydrogen-terminated field-effect transistors, MOSFETs, Schottky and p–i–n diodes, and related power-device architectures. Emerging opportunities in ultraviolet photodetectors, multifunctional electronics, and memory-oriented diamond devices are also briefly considered. Among the device classes reviewed, diamond diodes currently show the strongest evidence of high-voltage capability, whereas transistor development remains constrained by threshold-voltage control, normally off operation, contact resistance, interface stability, and reliability. Diamond is therefore more likely to complement than replace established SiC and GaN technologies, particularly in specialized high-field, high-temperature, radiation-rich, and chemically demanding applications. Broader deployment will require scalable low-defect wafers, reliable n-type doping, stable interfaces and contacts, and more cost-effective manufacturing.