Issue 11, 2024

Low-resistivity Ohmic contacts of Ti/Al on few-layered 1T′-MoTe2/2H-MoTe2 heterojunctions grown by chemical vapor deposition

Abstract

This study explores the phase-controlled growth of few-layered 2H-MoTe2, 1T′-MoTe2, and 2H-/1T′-MoTe2 heterostructures and their impacts on metal contact properties. Cold-wall chemical vapor deposition (CW-CVD) with varying growth rates of MoOx and reaction temperatures with Te vapors enabled the growth of continuous thin films of either 1T′-MoTe2 or 2H-MoTe2 phases on two-inch sapphire substrates. This methodology facilitates the meticulous optimization of chemical vapor deposition (CVD) parameters, enabling the realization of phase-controlled growth of few-layered MoTe2 thin films and their subsequent heterostructures. The study further investigates the influence of a 1T′-MoTe2 intermediate layer on the electrical properties of metal contacts on few-layered 2H-MoTe2. Bi-layer Ti/Al contacts directly deposited on 2H-MoTe2 exhibited Schottky behavior, indicating inefficient carrier transport. However, introducing a few-layered 1T′-MoTe2 intermediate layer between the metal and 2H-MoTe2 layers improved the contact characteristics significantly. The resulting Al/Ti/1T′-MoTe2/2H-MoTe2 contact scheme demonstrates Ohmic behavior with a specific contact resistance of around 1.7 × 10−4 Ω cm2. This substantial improvement is attributed to the high carrier concentration of the 1T′-MoTe2 intermediate layer which could be attributed tentatively to the increased tunneling events across the van der Waals gap and enhancing carrier transport between the metal and 2H-MoTe2.

Graphical abstract: Low-resistivity Ohmic contacts of Ti/Al on few-layered 1T′-MoTe2/2H-MoTe2 heterojunctions grown by chemical vapor deposition

Supplementary files

Article information

Article type
Communication
Submitted
19 Jul 2024
Accepted
09 Sep 2024
First published
11 Sep 2024

Nanoscale Horiz., 2024,9, 2060-2066

Low-resistivity Ohmic contacts of Ti/Al on few-layered 1T′-MoTe2/2H-MoTe2 heterojunctions grown by chemical vapor deposition

P. Chi, J. Wang, J. Zhang, Y. Chuang, M. Lee and J. Sheu, Nanoscale Horiz., 2024, 9, 2060 DOI: 10.1039/D4NH00347K

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