二维半导体器件电应力失效机制研究

Two-dimensional (2D) semiconductors are promising electronic materials for next-generation electronics due to the excellent electrical transport property, controllability of gate and compatibility with current CMOS fabrication technique. Currently, most of the researches are limited to synthesizing new 2D materials and developing novel devices, and less work has been focused on investigating the failure mechanism of 2D semiconductor devices, especially the impact of electrical stress on the performance and structure of 2D semiconductor devices. Studying electrical stress failure regularity of 2D semiconductor devices and conrresponding physical mechanism, and emphasizing reasonable material selection and device structure design are important for reducing the failure rate of the devices in the application and improving the reliability of the integrated circuits. In this project, we will fabricate field-effect transistors and photodetectors based on previous research on 2D semiconductor materials. Electrical pulse treatment will be carried on the pre-fabricated 2D semiconductor devices to creat invalid device models resulted from electrical stress. Then, cs-corrected transmission electron microscope will be adopted to systematically investigate the fine structure and component distribution of the metal-semiconductor interface. Finally, we will investigate the relationship between device performance degradation and material failure, and sum up the microscopic physical mechanism of 2D semiconductor device failure resulted from the electrical stress. The original innovative research can be expected to effectively promote the development and application of 2D semiconductor devices.

二维半导体材料拥有优异的电输运特性、栅控能力以及与当前CMOS加工工艺相兼容的特点，有望成为下一代电子学的关键电子材料。目前该领域的研究主要集中在新材料制备和新型器件开发，而有关二维半导体器件失效机制的研究仍是空白，特别是电应力对器件性能和结构的影响。研究二维半导体器件电应力失效规律及其物理机制，强调合理的材料选择与器件结构设计，对降低器件在应用中的失效率、提高集成电路的可靠性具有重要的意义。在本项目中，我们将在前期二维半导体材料研究基础上，制备性能良好的场效应晶体管和光电探测器；利用电脉冲信号处理二维半导体器件，创建因电应力作用而失效的物理模型；采用球差校正透射电镜调查器件中金属-二维半导体界面的精细结构与元素赋存状态；研究器件性能退化与材料失效之间的关系，揭示二维半导体器件电应力失效的微观物理机制。本项目研究工作具有原始创新性，将对二维半导体器件的发展与应用有重要的推动作用。

金属—二维半导体接触（欧姆接触或肖特基接触）是二维半导体电子器件和光电子器件的核心组成结构，两者间的界面特性直接决定了器件的接触电阻、器件效率、热稳定性以及器件的可靠性等，是当前二维材料研究领域中最前沿的课题之一。本项目围绕二维半导体器件，研究了不同脉冲电压对这些器件性能的影响，发现过电应力能够击穿器件界面，导致材料出现纳米尺度的孔洞结构，并且发生部分氧化。利用球差校正透射电镜表征，发现器件长时间工作后，单层和少层沟道材料会出现明显的硫或硒空位，缺陷增殖并随着工作时间不断地长大。通过提高二维材料厚度，并降低使用电压，可以有效地抑制器件失效。该项目的研究成果揭示了二维半导体器件电应力失效的微观机制，将对二维半导体器件的实际应用具有重要的推动作用。.