Theoretical dissection of the electronic anisotropy and quantum transport of ultrascaled halogenated borophene MOSFETs
Shiying Guo, Ying Wang, Hengze Qu, Wenhan Zhou, Yee Sin Ang, Shengli Zhang, Haibo Zeng
Abstract
Two-dimensional (2D) anisotropic semiconductors, such as black phosphorene, show strong potential in ultrascaled metal-oxide-semiconductor field-effect transistors (MOSFETs) as the anisotropic electronic structure is highly beneficial in boosting the device performance at sub-10-nm gate length regime. Metallic graphenelike borophene can be halogenated to form a stable monolayer family of ${\mathrm{B}}_{4}{\mathrm{X}}_{4}$ ($\mathrm{X}$ = $\mathrm{F},\phantom{\rule{0.2em}{0ex}}\mathrm{Cl},\phantom{\rule{0.2em}{0ex}}\mathrm{and}\phantom{\rule{0.2em}{0ex}}\mathrm{Br}$) whose highly anisotropic semiconducting electronic structures suggest a potential in ultrascaled MOSFET applications. Here, we computationally explore the quantum transport properties of ${\mathrm{B}}_{4}{\mathrm{X}}_{4}$ monolayers as high-performance (HP) 5-nm MOSFETs. The HP on-state current of the n-type 5-nm monolayer ${\mathrm{B}}_{4}{\mathrm{X}}_{4}$ MOSFETs can reach over 3000 \textmu{}A/\textmu{}m at 5-nm gate length regime, thus fulfilling the ITRS requirement of HP devices. Of note, by analyzing the physical relationship between the anisotropic electronic structures (transport effective mass ${m}_{//}$ and density of states ${m}_{\mathrm{DOS}}$), we show that large electronic anisotropy does not immediately guarantee high performance. An overly large ${m}_{//}$ or ${m}_{\mathrm{DOS}}$ would suppress the saturation current and lead to limited HP on-state current of monolayer ${\mathrm{B}}_{4}{\mathrm{X}}_{4}$, thus revealing a balance between the effective masses is needed when designing 2D semiconductor MOSFETs. This work provides insights and design guidelines for the development of next-generation nanoelectronic devices based on the exceptional transport properties of 2D anisotropic channel materials.