Department of Applied Physics, Sookmyung Women's University, Seoul 04310, Republic of Korea.
Nanotechnology. 2019 Jan 18;30(3):035206. doi: 10.1088/1361-6528/aae99c. Epub 2018 Nov 16.
Clean interface and low contact resistance are crucial requirements in two-dimensional (2D) materials to preserve their intrinsic carrier mobility. However, atomically thin 2D materials are sensitive to undesired Coulomb scatterers such as surface/interface adsorbates, metal-to-semiconductor Schottky barrier (SB), and ionic charges in the gate oxides, which often limits the understanding of the charge scattering mechanism in 2D electronic systems. Here, we present the effects of hafnium dioxide (HfO) high-κ passivation and SB height on the low-frequency (LF) noise characteristics of multilayer molybdenum ditelluride (MoTe) transistors. The passivated HfO passivation layer significantly suppresses the surface reaction and enhances dielectric screening effect, resulting in an excess electron n-doping, zero hysteresis, and substantial improvement in carrier mobility. After the high-κ HfO passivation, the obtained LF noise data appropriately demonstrates the transition of the Coulomb scattering mechanism from the SB contact to the channel, revealing the significant SB noise contribution to the 1/f noise. The substantial excess LF noise in the subthreshold regime is mainly attributed to the excess metal-to-MoTe SB noise and is fully eliminated at the high drain bias regime. This study provides a clear insight into the origin of electronic signal perturbation in 2D electronic systems.
界面清洁和低接触电阻是二维（2D）材料保持本征载流子迁移率的关键要求。然而，原子级薄的 2D 材料对不想要的库仑散射体很敏感，如表面/界面吸附物、金属-半导体肖特基势垒（SB）和栅极氧化物中的离子电荷，这通常限制了对 2D 电子系统中电荷散射机制的理解。在这里，我们展示了氧化铪（HfO）高介电常数钝化和 SB 高度对多层二碲化钼（MoTe）晶体管低频（LF）噪声特性的影响。钝化的 HfO 钝化层显著抑制了表面反应并增强了介电屏蔽效应，导致过量电子 n 掺杂、无迟滞和载流子迁移率的显著提高。在高介电常数 HfO 钝化之后，获得的 LF 噪声数据适当地展示了库仑散射机制从 SB 接触到沟道的转变，揭示了 SB 噪声对 1/f 噪声的显著贡献。亚阈值区的大量过剩 LF 噪声主要归因于过量的金属-MoTe SB 噪声，并在高漏极偏置区完全消除。本研究为二维电子系统中电子信号干扰的起源提供了清晰的认识。
