Physics of Fermi-Level "Unpinning" at Metal/Ge Interfaces; First-Principles View
Physics of Fermi-Level "Unpinning" at Metal/Ge Interfaces; First-Principles View
复制标题
金属/Ge界面费米能级“脱钉”物理学；
DOI：
10.1149/08607.0291ecst
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
T. Nishimoto
中科院分区：
文献类型：
--
作者：
T. Nakayama;T. Nishimoto
金属/Ge界面费米能级位置的控制是研制下一代Ge器件需要克服的问题之一。本文首先用第一性原理计算方法研究了各种TiN/Ge界面上的肖特基势垒，发现在干净的TiN/Ge界面上发生了费米列夫钉扎，而在富N的TiN/Ge界面上发生了钉扎断裂，这与实验结果一致。对电子结构的分析表明，TiN_2、Ge3N_4等富N界面层的出现实现了脱钉。其次，我们比较了不同金属/Ge界面的脱钉特征，结果表明，Ge界面键的终止消除了界面Ge层中能隙态的电子自由，促进了脱钉。
The control of Fermi-energy position at metal/Ge interface is one of issues to be overcome for developing next-generation Ge devices. In this work, at first, we study the Schottky barrier at various TiN/Ge interfaces by the first-principles calculation and show that the Fermilevel pinning occurs at clean TiN/Ge interface, while the pinning is broken, ie, the depinning occurs, at N-rich TiN/Ge interface, in agreement with experiments. By analyzing electronic structures, we show that the appearance of N-rich interface layers such as TiN2 and Ge3N4 layers realizes the depinning. Next, we compare the depinning features at various metal/Ge interfaces and show that the termination of interface bonds of Ge eliminates the electronic freedom of gap states in interface Ge layers and promotes the depinning.