Kim DongHwan, Oh Guen Hyung, Kim Ansoon, Shin ChaeHo, Park Jonghoo, Kim Sang-Il, Kim TaeWan
Materials and Convergence Metrology Institute, Korea Research Institute of Standards and Science, Daejeon 34113, South Korea.
Department of Electrical Engineering and Smart Grid Research Center, Jeonbuk National University, Jeonju 54896, South Korea.
ACS Appl Mater Interfaces. 2020 Sep 9;12(36):40518-40524. doi: 10.1021/acsami.0c11154. Epub 2020 Aug 29.
Ternary alloys in two-dimensional (2D) transition-metal dichalcogenides allow band gap tuning and phase engineering and change the electrical transport type. A process of 2D van der Waals epitaxial growth of molybdenum sulfide telluride alloys (MoSTe, 0 ≤ ≤ 1) is presented for synthesizing few-atomic-layer films on SiO substrates using metal-organic chemical vapor deposition. Raman spectra, X-ray photoelectron spectra, photoluminescence (PL), and electrical transport properties of few-atomic-layer MoSTe (0 ≤ ≤ 1) films are systematically investigated. The strong PL peaks at 80 K from MoSTe (0.45 ≤ ≤ 0.93) reveal a composition-controllable optical band gap ( = 1.55-1.91 eV at 80 K). Electrical transport properties of MoSTe alloys, where 0 ≤ ≤ 0.8 and 0.93 ≤ ≤ 1, exhibit p-type and n-type semiconducting behaviors, respectively. Remarkably, an increase in the Te composition of a few-atomic-layer MoSTe (0 ≤ ≤ 1) film left-shifts the threshold voltage of a MoSTe (0 ≤ ≤ 1) field-effect transistor. The narrower band gap energies of MoSTe films with higher Te content cause a decrease in the on/off current ratios.
二维（2D）过渡金属二硫属化物中的三元合金可实现带隙调节和相工程，并改变电输运类型。本文介绍了一种硫化钼碲化物合金（MoSTe，0≤≤1）的二维范德华外延生长过程，该过程使用金属有机化学气相沉积法在SiO衬底上合成少原子层薄膜。系统研究了少原子层MoSTe（0≤≤1）薄膜的拉曼光谱、X射线光电子能谱、光致发光（PL）和电输运性质。MoSTe（0.45≤≤0.93）在80K时的强PL峰揭示了一个可通过成分控制的光学带隙（80K时=1.55 - 1.91eV）。MoSTe合金（0≤≤0.8和0.93≤≤1）的电输运性质分别表现出p型和n型半导体行为。值得注意的是，少原子层MoSTe（0≤≤1）薄膜中Te成分的增加会使MoSTe（0≤≤1）场效应晶体管的阈值电压左移。Te含量较高的MoSTe薄膜的带隙能量变窄导致开/关电流比降低。
