Designing high-efficiency metal and semimetal contacts to two-dimensional semiconductor γ-GeSe.

Forming a low-resistance semiconductor–metal contact is a critical step to achieve a high-performance two-dimensional (2D) semiconductor nanoelectronic device. Motivated by the recent discovery of monolayer γ-GeSe with exceptional high electrical conductivity reaching 10⁵ S/m, we computationally investigate the interface contact properties of γ-GeSe with four representative classes of metallic systems, including 2D semimetal (graphene), 2D metal (NbS₂), 3D semimetal (Bi), and 3D metal (Au) using first-principle density functional theory simulations. We found that these metals exhibit rich contact formation physics with 2D γ-GeSe, yielding contacts of heterostructures with weak and moderate couplings. Importantly, γ-GeSe/NbS₂ is an Ohmic contact while γ-GeSe/Bi is an n-type Schottky contact with an ultralow barrier height of 0.07 eV. For γ-GeSe/graphene contact, the electronic properties can be adjusted via the interlayer distance or via an external electric field. Finally, we show that the contact properties can also be further controlled using layer-number engineering of γ-GeSe. Our findings provide a useful guideline for designing high-performance 2D nanoelectronics based on 2D γ-GeSe. [ABSTRACT FROM AUTHOR]