N- and P-type doping of diamonds: A review

Diamond has been one of the most investigated ultrawide bandgap (UWBG) semiconductors for optoelectronics, superconductors, energy, and quantum applications for almost half of a century owing to its unique properties. Diamonds' intrinsic features-a large bandgap (5.47 eV), an extremely high breakdown voltage (10 MV/cm), the highest thermal conductivity (2200 W/m-K), and very high radiation-tolerance, make them promising for high-power, high-frequency devices suitable for high-temperature and extreme radiation environments. Since the demand for high-speed consumer electronics with large power and faster data handling capacity is rising at an unprecedented rate in the post-COVID era, diamonds' excellent mobility of electrons and holes (4500 and 3800 cm²/V-s) make them ideal for servers and systems. To materialize these multipurpose devices with higher efficiency and endurance than Si and SiC-based technologies, diamonds with good p- and n-type conductivity are needed. Therefore, nearly several decades-long efforts have been devoted to understanding and controlling the carrier conductivities in diamonds. Furthermore, diamonds' color centers' remarkable application as the qubit for next-generation quantum computers has also sparked interest in investigating diamond point defects at the quantum level. Hence, it is necessary to comprehensively study the fabrication, doping, and applications in semiconducting and quantum devices to stay relevant to the diamond revolution and thus advance this flourishing field. Therefore, this review article summarizes the current status and breakthroughs in diamond doping and devices fabricated using doped diamonds to provide an overview of the challenges and successes in using this highly promising UWBG material in electronic, superconducting, and quantum applications.