State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University , Shanghai 200433, P. R. China.
ACS Appl Mater Interfaces. 2017 Aug 16;9(32):26996-27003. doi: 10.1021/acsami.7b06160. Epub 2017 Aug 2.
HfS is one of the emerging transition metal dichalcogenides and is very promising for low-power nanoelectronics and high-sensitivity optoelectronic device applications. We studied the band structures of 1T-HfS with different thicknesses by first principles simulation, and the impact of different metal contacts to the HfS device performance has been experimentally studied. Back-gate and top-gate HfS field-effect transistors (FETs) were fabricated, and better electrical characteristics have been achieved with the FETs with the Ti/Au contact as compared with the Pt-contacted FETs. Thin layers of Pt and Ti/Au films were deposited on HfS flakes to investigate the metal/HfS interface by using scanning electron microscopy, atomic force microscopy, and Raman spectroscopy. A smoother Ti/Au film was formed on HfS, resulting in higher carrier injection and transport efficiency. The phonon behavior being dominated by the interface chemical bonding at the Ti/Au contact region has been confirmed with the more sensitive A phonon mode from the bilayer HfS.
HfS 是一种新兴的过渡金属二卤化物，非常适合低功耗纳米电子学和高灵敏度光电设备应用。我们通过第一性原理模拟研究了不同厚度的 1T-HfS 的能带结构，并实验研究了不同金属接触对 HfS 器件性能的影响。制备了背栅和顶栅 HfS 场效应晶体管 (FET)，与 Pt 接触的 FET 相比，具有 Ti/Au 接触的 FET 具有更好的电学特性。在 HfS 薄片上沉积了薄的 Pt 和 Ti/Au 薄膜，通过扫描电子显微镜、原子力显微镜和拉曼光谱研究了金属/HfS 界面。在 HfS 上形成了更平滑的 Ti/Au 薄膜，从而提高了载流子注入和输运效率。Ti/Au 接触区域的界面化学键合主导了声子行为，这一点从双层 HfS 的更敏感的 A 声子模式得到了证实。
