Band Alignment Tuning in Diamond (100)/CNT Heterostructures via Surface Passivation: First-Principles Design for High-Power Nanoelectronics

Benefiting from the high electron mobility and ultra-thin geometric features, carbon nanotubes (CNTs) exhibit great potential as semiconductor channel materials in micro/nano electronic devices. Diamond (Dia), with superior hardness and chemical inertness, is an ideal substrate material for CNT-based electronic devices. In this study, using the first-principles calculations, we systematically investigate the effect of surface reconstruction and passivation on the electronic structure of the heterojunction formed by Dia (100) surface and CNT, as well as the associated band alignment at the interface. Our calculations indicate that surface reconstruction and passivation treatments could facilitate the formation of a type-I heterojunction between Dia (100) and CNT, which meet the performance criteria required for CNT-based electronic applications. More importantly, oxygen passivation could result in both the conduction band offset (CBO) and valence band offset (VBO) between Dia (100) and CNT being greater than 1.0 eV. The findings presented in this work demonstrate the critical role of surface reconstruction and passivation in enhancing the performance of CNT-based high-performance radio frequency (RF) and optoelectronic devices. They also provide valuable insights for optimizing CNT field-effect transistor (FET) interfaces.