Tunable n-Type Conductivity and Transport Properties of Cubic Boron Nitride via Carbon Doping

The recent discovery of direct conversion of hexagonal boron nitride (h-BN) into quenched BN (Q-BN) and single-crystal cubic BN (c-BN) by pulsed laser annealing (PLA) have been implemented to fabricate carbon-doped c-BN with dopant concentration ranging from 2 × 1019 to 7 × 1021 cm–3. Micro Raman analysis shows a total conversion of h-BN into phase-pure c-BN, whereas the X-ray diffraction (XRD) confirms the presence of the cubic structure with (111) epitaxy on c-sapphire. Hall measurements demonstrate the n-type electrical property, and the temperature-dependent resistivity measurements confirm the semiconductor-like profile of the doped c-BN. Consistent changes in resistivity, Hall mobility, and other electrical properties were investigated with the variance in dopant concentration level. We have observed a shift in the conduction mechanism with temperature from the resistivity vs temperature analyses. At the high-temperature regime (130–330 K), the activation energy lies in between 0.012 and 0.074 eV, whereas at the low-temperature regime (20–130 K), the activation energy was obtained to be in between 0.0024 and 0.0083 eV. The lower values of activation energies, showing a complete ionization of the impurity atoms even at room temperature, are surmised to result from dopant-profile broadening. The enhanced electrical activation and superior quality c-BN films open exciting avenues for next-generation device applications.