Single-crystal diamond grown through high-power-density epitaxy used for a high-performance radiation detector

Radiation detectors are important device-level characterization tools of the carrier dynamics of diamond as an ultrawide-bandgap semiconductor. Herein, a high-quality single-crystal diamond was grown on a high-temperature and high-pressure diamond substrate through microwave plasma chemical vapor deposition. We achieved the enhancement of microwave power density by compressing a plasma ball and optimizing the carbon-hydrogen ratio (C/H) within the plasma and thus considerably diminished the impurity and dislocation densities of the diamond epilayer. The full width at half maximum of the X-ray (004) reflection rocking curve was 15 arcsec, and no impurity emission bands were detectable in the photoluminescence spectrum at room temperature (25°C). The radiation detector made from this 200-µm-thick diamond epifilm demonstrated an α-particle response with a charge collection efficiency of 97.03% and energy resolutions of 2.1% for electrons and 97.86% and 1.5% for holes. Furthermore, the product of mobility and lifetime of electrons and holes reached 8 × 10⁻⁵ and 4.1 × 10⁻⁴ cm² V⁻¹, respectively. The epitaxial method reduces costs while fulfilling the stringent requirements of radiation detection for commercial applications.