Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
ACS Nano. 2016 Jul 26;10(7):6853-60. doi: 10.1021/acsnano.6b02521. Epub 2016 Jun 22.
Transition metal dichalcogenides (TMDCs) have been extensively explored for applications in electronic and optoelectronic devices due to their unique material properties. However, the presence of large contact resistances is still a fundamental challenge in the field. In this work, we study defect engineering by using a mild plasma treatment (He or H2) as an approach to reduce the contact resistance to WSe2. Material characterization by X-ray photoelectron spectroscopy, photoluminescence, and Kelvin probe force microscopy confirm defect-induced n-doping, up to degenerate level, which is attributed to the creation of anion (Se) vacancies. The plasma treatment is adopted in the fabrication process flow of WSe2 n-type metal-oxide-semiconductor field-effect transistors to selectively create anion vacancies at the metal contact regions. Due to lowering the metal contact resistance, improvements in the device performance metrics such as a 20× improvement in ON current and a nearly ideal subthreshold swing value of 66 mV/dec are observed. This work demonstrates that defect engineering at the contact regions can be utilized as a reliable scheme to realize high-performance electronic and optoelectronic TMDC devices.
过渡金属二卤化物（TMDCs）由于其独特的材料特性，在电子和光电子器件的应用中得到了广泛的研究。然而，大接触电阻的存在仍然是该领域的一个基本挑战。在这项工作中，我们通过使用温和的等离子体处理（He 或 H2）来研究缺陷工程，作为一种降低 WSe2 接触电阻的方法。X 射线光电子能谱、光致发光和 Kelvin 探针力显微镜的材料特性证实了缺陷诱导的 n 型掺杂，达到了简并水平，这归因于阴离子（Se）空位的形成。等离子体处理被应用于 WSe2 n 型金属-氧化物-半导体场效应晶体管的制造工艺中，以在金属接触区域选择性地产生阴离子空位。由于降低了金属接触电阻，观察到器件性能指标的改善，例如导通电流提高了 20 倍，亚阈值摆幅值接近理想的 66 mV/dec。这项工作表明，在接触区域进行缺陷工程可以作为一种可靠的方案，实现高性能的电子和光电子 TMDC 器件。
