School of Physics and Telecommunication Engineering, Shaanxi Key Laboratory of Catalysis, Shaanxi University of Technology, Hanzhong 723001, P. R. China.
Phys Chem Chem Phys. 2018 Oct 7;20(37):24239-24249. doi: 10.1039/c8cp04759f. Epub 2018 Sep 13.
Recently, two-dimensional (2D) gallium nitride (GaN) was experimentally fabricated, and has promising applications in next-generation electronic and optoelectronic devices. A direct contact with metals to inject the carrier is often required for potential 2D GaN devices. Herein, the first systematic study on the interface properties of monolayer (ML) planar and buckled GaN with different metal electrodes (Al, Ti, Ag, Au, Sc, and Pt) in a field-effect transistor framework is presented using first-principles energy band calculations and quantum transport simulations. Because of moderate Fermi level pinning (electron pinning factor S = 0.63), ML planar GaN and the Ag electrode form an n-type lateral Schottky contact, while ML planar GaN and Ti, Al, and Au electrodes form a p-type lateral Schottky contact. The ML buckled GaN, Ag, Al, Ti, and Sc electrodes form a p-type lateral Schottky contact as a result of Fermi level pinning with a hole pinning factor of S = 0.75. Notably, a highly desirable n-type/p-type lateral ohmic contact is formed at the lateral interface of the ML planar GaN and Sc/Pt electrodes, and a p-type lateral ohmic contact is formed at the lateral interface of the ML buckled GaN and Pt/Au electrodes. Therefore, a low resistance contact can be realized in ML planar and buckled GaN devices.
最近，实验制备了二维（2D）氮化镓（GaN），并在下一代电子和光电子器件中具有广阔的应用前景。对于潜在的 2D GaN 器件，通常需要与金属直接接触以注入载流子。在此，通过第一性原理能带计算和量子输运模拟，在晶体管结构中首次对具有不同金属电极（Al、Ti、Ag、Au、Sc 和 Pt）的单层（ML）平面和褶皱 GaN 的界面性质进行了系统研究。由于中等的费米能级钉扎（电子钉扎因子 S = 0.63），ML 平面 GaN 和 Ag 电极形成 n 型横向肖特基接触，而 ML 平面 GaN 和 Ti、Al 和 Au 电极形成 p 型横向肖特基接触。由于费米能级钉扎和空穴钉扎因子 S = 0.75，ML 褶皱 GaN、Ag、Al、Ti 和 Sc 电极形成 p 型横向肖特基接触。值得注意的是，在 ML 平面 GaN 和 Sc/Pt 电极的横向界面形成了理想的 n 型/p 型横向欧姆接触，而在 ML 褶皱 GaN 和 Pt/Au 电极的横向界面形成了 p 型横向欧姆接触。因此，可以在 ML 平面和褶皱 GaN 器件中实现低电阻接触。
