Mechanistic Understanding and Demonstration of Direct Chemical Vapor Deposition of Transition Metal Dichalcogenides Across Metal Contacts

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) remain a topic of immense interest. Given their low operational switching energy costs, there is immense opportunity for niche applications in new computing architectures with the promise of continued miniaturization. However, deleterious and time-consuming transfer processes and multiple channel/contact engineering steps can substantially degrade device performance. This work demonstrates kinetics-governed in situ growth regimes (surface or edge growth from gold) of WSe2 and provides a mechanistic understanding of these regimes via energetics across various material interfaces. As a proof-of-concept, field effect transistors (FET) with an in situ grown WSe2 channel across Au contacts are fabricated directly via chemical vapor deposition, demonstrating a 2D semiconductor transistor via a “transfer-free” method. We leverage directional edge growth to fabricate contacts with robust thickness-dependent Schottky-to-Ohmic behavior.