Quantum transport of a two-dimensional hole gas in a diamond/h-BN heterostructure

Diamond attracts increasing attention as a next-generation semiconducting material because of its fascinating properties such as a wide-band gap, high thermal conductivity, high breakdown electric field, and high mobility. In this study, we fabricated a p-type diamond field-effect transistor (FET) using a diamond/hexagonal boron nitride (h-BN) heterostructure. A single-crystalline h-BN was cleaved by the scotch tape method and laminated on a hydrogen-terminated diamond surface. The laminated h-BN flake was used as a gate dielectric. The excellent insulating properties of h-BN enabled the mobilities of holes accumulating at the diamond surface to be higher than 300 cm²V^-1s^-1 at room temperature for hole densities above 5×10¹² cm^-2. The high mobility allowed to observe Shubnikov–de Haas oscillations in both the longitudinal and Hall resistivities. The oscillations provided valuable information on the hole transport at the diamond surface, such as the cyclotron effective mass, quantum lifetime, and two dimensionality. The high-quality two-dimensional hole gas demonstrated in this study will lead to new studies of quantum transport in diamond and development of high-performance diamond electric devices. (Y. Sasama et al., APL mater. 6 111105 (2018), arXiv:1907.13500)