Charge Carrier Transport Properties in Layered Structure of Hexagonal Boron Nitride ($h$-BN) and Thermal Neutron Detection Based on $h$-BN

Hexagonal boron nitride (h-BN) epilayers have been synthesized by MOCVD. It was found that the carrier mobility in h-BN epilayers is strongly dependent on temperature following the power law $\mu \quad \sim $ T$^{\mathrm{-\alpha }}$ with $\alpha \quad \approx $ 3.02, satisfying the 2D carrier transport limit dominated by the polar optical phonon scattering The deduced maximum energy (wave number) of the optical phonon is $\sim $ 192 meV (or 1546 cm$^{\mathrm{-1}})$. The measured carrier mobility-lifetime ($\mu \tau )$ product of $h$-BN thin films grown on sapphire substrate is 2.83 x 10$^{\mathrm{-7}}$ cm$^{\mathrm{2}}$/V for electrons and holes, which is comparable to that of GaN films grown on sapphire. Thermal neutron detectors based on $h$-BN epilayers were fabricated and the reaction product pulse-height spectra were measured under thermal neutron irradiation produced by $^{\mathrm{252}}$Cf source. It was shown that $h$-BN thin film thermal neutron detectors are capable to resolve specific nuclear reaction products with unprecedentedly high energy resolution.