Pervasive Ohmic Contacts in Bilayer Bi2O2Se-Metal Interfaces
Pervasive Ohmic Contacts in Bilayer Bi2O2Se-Metal Interfaces
复制标题
双层 Bi2O2Se-金属界面中普遍存在的欧姆接触
DOI：
10.1021/acs.jpcc.8b12278
复制
发表时间：
2019
影响因子：
3.7
通讯作者：
Lu Jing
中科院分区：
文献类型：
--
作者：
Xu Lianqiang;Liu Shiqi;Yang Jie;Shi Bowen;Pan Yuanyuan;Zhang Xiuying;Li Hong;Yan Jiahuan;Li Jingzhen;Yang Jinbo;Lu Jing
由于其出色的栅极静电性能，二维 (2D) 半导体材料被认为是下一代场效应晶体管 (FET) 中很有前途的沟道材料。然而，二维半导体-金属界面处经常存在的肖特基势垒会明显降低器件性能。最近，合成了二维层状半导体氧硒化铋（Bi2O2Se），并表现出高载流子迁移率和优异的空气稳定性。我们首次对双层 (BL) Bi2O2Se 与六种金属（Sc、Ti、Ag、Au、Pd 和 Pt）接触的界面性质进行了系统探索，通过基于密度泛函理论的能带结构计算和 FET 配置中的量子输运模拟，覆盖了广泛的功函数范围。值得注意的是，我们的结果表明，由于界面处存在强大的超间隙费米能级钉扎，横向方向上的所有接触都是 n 型欧姆。实验上，具有 Au/Pd 电极的实际 BL Bi2O2Se FET 确实显示出 n 型欧姆接触。因此，BL Bi2O2Se 器件可以轻松实现低接触电阻。
Due to their outstanding gate electrostatics, two-dimensional (2D) semiconducting materials are regarded as promising channel materials used in the next-generation field-effect transistors (FETs). However, a Schottky barrier often existing at the 2D semiconductor–metal interface can evidently degrade the device performance. Very lately, 2D layered semiconducting bismuth oxyselenide (Bi2O2Se) is synthesized and exhibits high carrier mobility and excellent air stability. We conduct a systematic exploration, for the first time, on the interfacial nature of bilayer (BL) Bi2O2Se in contact with six metals (Sc, Ti, Ag, Au, Pd, and Pt) that cover a wide work function range by density functional theory-based band structure calculations and quantum transport simulations in a FET configuration. Remarkably, our results reveal that all the contacts in the lateral direction are n-type Ohmic due to the robust beyond-gap Fermi level pinning at the interface. Experimentally, the actual BL Bi2O2Se FET with a Au/Pd electrode indeed shows an n-type Ohmic contact. Hence, low contact resistance can easily be expected in BL Bi2O2Se devices.