Fizika Nizkikh Temperatur: Volume 45, Number 11 (November 2019), p. 1345-1359 ( to contents , go back )
Two-dimensional hole transport in ion-gated diamond surfaces: a brief review (Review Article)
Erik Piatti, Davide Romanin, Dario Daghero, and Renato S. Gonnelli
Department of Applied Science and Technology, Politecnico di Torino, I-10129 Torino, Italy
Received July 16, 2019, published online September 27, 2019
Electrically-conducting diamond is a promising candidate for next-generation electronic, thermal and electrochemical applications. One of the major obstacles towards its exploitation is the strong degradation that some of its key physical properties — such as the carrier mobility and the superconducting transition temperature — undergo upon the introduction of disorder. This makes the two-dimensional hole gas induced at its surface by electric field-effect doping particularly interesting from both a fundamental and an applied perspective, since it strongly reduces the amount of extrinsic disorder with respect to the standard boron substitution. In this short review, we summarize the main results achieved so far in controlling the electric transport properties of different field-effect doped diamond surfaces via the ionic gating technique. We analyze how ionic gating can tune their conductivity, carrier density and mobility, and drive the different surfaces across the insulator-to-metal transi-tion. We review their strongly orientation-dependent magnetotransport properties, with a particular focus on the gate-tunable spin-orbit coupling shown by the (100) surface. Finally, we discuss the possibility of field-induced superconductivity in the (110) and (111) surfaces as predicted by density functional theory calculations.
Key words: transport properties of diamond surfaces, field-effect doping, ionic gating technique.