Atomic Layer MoS2 xTe2(1- x) Ternary Alloys: Two-Dimensional van der Waals Growth, Band gap Engineering, and Electrical Transport

DongHwan Kim; Guen Hyung Oh; Ansoon Kim; ChaeHo Shin; Jonghoo Park; Sang-Il Kim; TaeWan Kim

doi:10.1021/acsami.0c11154

Atomic Layer MoS_{2 x}Te_{2(1- x)} Ternary Alloys: Two-Dimensional van der Waals Growth, Band gap Engineering, and Electrical Transport

ACS Appl Mater Interfaces. 2020 Sep 9;12(36):40518-40524. doi: 10.1021/acsami.0c11154. Epub 2020 Aug 29.

Authors

DongHwan Kim¹, Guen Hyung Oh², Ansoon Kim¹, ChaeHo Shin¹, Jonghoo Park³, Sang-Il Kim⁴, TaeWan Kim²

Affiliations

¹ Materials and Convergence Metrology Institute, Korea Research Institute of Standards and Science, Daejeon 34113, South Korea.
² Department of Electrical Engineering and Smart Grid Research Center, Jeonbuk National University, Jeonju 54896, South Korea.
³ Department of Electrical Engineering, Kyungpook National University, Daegu 41566, South Korea.
⁴ Department of Materials Science and Engineering, University of Seoul, 163 Seoulsiripdae-ro, Dongdaemun-gu, Seoul 02504, South Korea.

PMID: 32808524
DOI: 10.1021/acsami.0c11154

Abstract

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 (MoS_2xTe_2(1-x), 0 ≤ x ≤ 1) is presented for synthesizing few-atomic-layer films on SiO₂ substrates using metal-organic chemical vapor deposition. Raman spectra, X-ray photoelectron spectra, photoluminescence (PL), and electrical transport properties of few-atomic-layer MoS_2xTe_2(1-x) (0 ≤ x ≤ 1) films are systematically investigated. The strong PL peaks at 80 K from MoS_2xTe_2(1-x) (0.45 ≤ x ≤ 0.93) reveal a composition-controllable optical band gap (E_g = 1.55-1.91 eV at 80 K). Electrical transport properties of MoS_2xTe_2(1-x) alloys, where 0 ≤ x ≤ 0.8 and 0.93 ≤ x ≤ 1, exhibit p-type and n-type semiconducting behaviors, respectively. Remarkably, an increase in the Te composition of a few-atomic-layer MoS_2xTe_2(1-x) (0 ≤ x ≤ 1) film left-shifts the threshold voltage of a MoS_2xTe_2(1-x) (0 ≤ x ≤ 1) field-effect transistor. The narrower band gap energies of MoS_2xTe_2(1-x) films with higher Te content cause a decrease in the on/off current ratios.

Keywords: MoSTe; field-effect transistor; metal−organic chemical vapor deposition; ternary alloy; wafer-scale synthesis.