摘要
基于硅基材料的逻辑器件由于其短沟道效应,使摩尔定律失效,二维半导体材料被认为是继续缩小晶体管尺寸以生产更多摩尔电子器件的潜在沟道材料.最近在实验上突破了技术瓶颈的限制,实现了二维场效应晶体管突破亚1 nm沟道极限,并且表现出优异的器件性能.这极大地鼓舞了在理论上进一步探索二维器件的性能.二维SnS具有较高的载流子迁移率和各向异性的电子性能,且材料性能环境稳定.本文应用第一性原理研究了亚5 nm SnS场效应晶体管的量子输运特性,鉴于SnS的各向异性,本文将器件沿单层SnS的armchair和zigzag两个方向进行构造,发现p型zigzag方向的器件性能优于其他类型(包括n型、p型的armchair方向和n型的zigzag方向).p型zigzag方向器件的开态电流在栅长缩短到1 nm也能满足国际半导体技术路线图的高性能(HP)器件要求,其值高达1934μA/μm.这在目前报道的1 nm栅长上的器件材料性能方面处于领先.
Abstract
Currently,Si-based field-effect transistors(FET)are approaching their physical limit and challenging Moore's law due to their short-channel effect,and further reducing their gate length to the sub-10 nm is extremely difficult.Two-dimensional(2D)layered semiconductors with atom-scale uniform thickness and no dangling bonds on the interface are considered potential channel materials to support further miniaturization and integrated electronics.Wu et al.[Wu F,et al.2022 Nature 603 259]successfully fabricated an FET with gate length less than 1 nm by using atomically thin molybdenum disulfide with excellent device performance.This breakthrough has greatly encouraged further theoretical predictions regarding the performance of 2D devices.Additionally,2D SnS has high carrier mobility,anisotropic electronic properties,and is stable under ambient condition,which is conducive to advanced applications in 2D semiconductor technology.Herein,we explore the quantum transport properties of sub-5 nm monolayer(ML)SnS FET by using first-principles quantum transport simulation.Considering the anisotropic electronic SnS,the double-gated-two-probe device model is constructed along the armchair direction and the zigzag direction of ML SnS.After testing five kinds of doping concentrations,a doping concentration of 5x1013 cm-2 is the best one for SnS FET.We also use the underlaps(ULs)with lengths of 0,2,and 4 nm to improve the device performance.On-state current(Ion)is an important parameter for evaluating the transition speed of a logic device.A higher Ion of a device can help to increase the switching speed of high-performance(HP)servers.The main conclusions are drawn as follows.1)Ion values of the n-type 2 nm(UL=4 armchair),3 nm(UL=2),4 nm(UL=3),5 nm(UL=0)and the p-type 1 nm(UL=2 zigzag),2 nm(UL=2 zigzag),3 nm(UL=2,4 zigzag),4 nm(UL=2,4 zigzag),and 5 nm(UL=0,armchair/zigzag)gate-length devices can meet the standards for HP applications in the next decade in the International Technology Roadmap for semiconductors(ITRS,2013 version).2)Ion values of the n-type device along the armchair direction(31-2369 μA/μm)are larger than those in the zigzag direction(4.04-1943 μA/μm),while Ion values of the p-type along the zigzag direction(545-4119 μA/μm)are larger than those in the armchair direction(0.7-924 μA/μm).Therefore,the p-type ML GeSe MOSFETs have a predominantly anisotropic current.3)Ion value of the p-type 3 nm gate-length(UL=0)device along the zigzag direction has the highest value 4119 μA/μm,which is 2.93 times larger than that in the same gate-length UL=2(1407 μA/μm).Hence,an overlong UL will weaken the performance of the device because the gate of the device cannot well control the UL region.Thus,a suitable length of UL for FET is very important.4)Remarkably,Ion values of the p-type devices(zigzag),even with a gate-length of 1 nm,can meet the requirements of HP applications in the ITRS for the next decade,with a value as high as 1934 μA/μm.To our knowledge,this is the best-performing device material reported at a gate length of 1 nm.5)Subthreshold swing(SS)evaluates the control ability of the gate in the subthreshold region.The better the gate control,the smaller the SS of the device is.The limit of SS for traditional FET is 60 mV/dec(at room temperature).Values of SS for ML SnS FET alone zigzag direction are less than those along the armchair direction because the leakage current is influenced by the effective mass.
基金项目
国家自然科学基金(Z20230015)
国家自然科学基金(12174238)
陕西省自然科学基础研究计划项目(2022JM-051)
陕西理工大学人才引进项目(SLGRC202401)
维普
万方数据