不同相NbS_(2)与GeS_(2)构成的二维金属-半导体异质结的电接触性质  

Electrical contact properties of 2D metal-semiconductor heterojunctions composed of different phases of NbS_(2)and GeS_(2)

作　　者：李景辉 曹胜果 韩佳凝 李占海 张振华[1] Li Jing-Hui;Cao Sheng-Guo;Han Jia-Ning;Li Zhan-Hai;Zhang Zhen-Hua(Hunan Provincial Key Laboratory of Flexible Electronic Materials Genome Engineering,Changsha University of Science and Technology,Changsha 410114,China)

机构地区：[1]长沙理工大学,柔性电子材料基因工程湖南省重点实验室,长沙410114

出　　处：《物理学报》2024年第13期238-250,共13页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61771076)资助的课题。

摘　　要：金属-半导体异质结(MSJ)是研发新型器件的基础.本文考虑利用不同相的金属H-和T-NbS_(2)与半导体GeS_(2)组成不同的二维范德瓦耳斯MSJ,并对它们的结构稳定性、电子特性以及电接触性质进行深入研究,重点在探索MSJ电接触性质对不同相金属的依赖关系.计算的结合能、声子谱、AIMD模拟以及力学性质研究表明,两异质结高度稳定,可实验制备,且用于电子器件设计可行.本征态H-NbS_(2)/GeS_(2)和T-NbS_(2)/GeS_(2)异质结分别形成了p型肖特基接触和准n型欧姆接触.同时发现它们的肖特基势垒高度(SBH)和电接触类型可以通过外加电场和双轴应变来有效调控.例如,对于H-NbS_(2)/GeS_(2)异质结,无论施加正/负电场或平面双轴压缩,均能实现欧姆接触,而T-NbS_(2)/GeS_(2)异质结,仅在施加负电场时,才能实现欧姆接触,但需要的负电场很低,平面双轴拉伸能导致其实现准欧姆接触.也就是说,当以半导体GeS_(2)单层为场效应晶体管沟道材料,与不同相的金属NbS_(2)接触形成MSJ时,其界面肖特基势垒有明显区别,且在不同情形(本征或物理调控)中各有优势.所以,本研究对于理解H(T)-NbS_(2)/GeS_(2)异质结电接触的物理机制具有重要意义,特别是为如何选择合适金属电极以研发高性能电子器件提供了理论参考.Metal-semiconductor heterojunction(MSJ)is the basis for developing novel devices.Here,we consider different two-dimensional van der Waals MSJs consisting of different-phase metals H-and T-NbS_(2)and semiconductor GeS_(2),and conduct an in-depth study of their structural stabilities,electronic and electrical contact properties,with an emphasis on exploring the dependence of the electrical contact properties of the MSJs on the different phases of metals.Calculation results of their binding energy,phonon spectra,AIMD simulations,and mechanical properties show that both heterojunctions are highly stable,which implies that it is possible to prepare them experimentally and feasible to use them for designing electronic devices.The intrinsic H-NbS_(2)/GeS_(2)and T-NbS_(2)/GeS_(2)heterojunctions form p-type Schottky contacts and quasi-n-type Ohmic contacts,respectively.It is also found that their Schottky barrier heights(SBHs)and electrical contact types can be effectively modulated by an applied electric field and biaxial strain.For example,for the H-NbS_(2)/GeS_(2)heterojunction,Ohmic contact can be achieved regardless of applying a positive/negative electric field or planar biaxial compression,while for the T-NbS_(2)/GeS_(2)heteroj unction,Ohmic contact can be achieved only at a very low negative electric field.The planar biaxial stretching can achieve quasi-Ohmic contact.In other words,when the semiconductor GeS_(2)monolayer is used as the channel material of the field effect transistor and contacts different metal NbS_(2)monolayers to form the MSJ,the interfacial Schottky barriers are distinctly different,and each of them has its own advantages in different situations(intrinsic or physically regulated).Therefore,this study is of great significance for understanding the physical mechanism of the electrical contact behaviors for H(T)-NbS_(2)/GeS_(2)heteroj unction,especially for providing the theoretical reference for selecting suitable metal electrodes for the development of high-performance electronic devices.

关 键 词：金属-半导体异质结 肖特基势垒 肖特基接触 欧姆接触 物理场调控 

分 类 号：O469[理学—凝聚态物理]