Vertical charge transport through transition metal dichalcogenides – a quantitative analysis

Abstract

Based on the careful design of two-terminal devices from multi-layer transition metal dichalcogenides (TMDs) such as MoS₂ and WSe₂, truly vertical transport has been experimentally evaluated and theoretically analyzed. By exploring, the electric field and temperature dependence of in total 28 TMD devices of various thicknesses, a model that describes vertical transport as Fowler Nordheim mediated at high electric fields and thermal injection dominated at low fields has been developed. Our approach is similar to the description chosen to capture gate leakage current levels through amorphous materials such as SiO₂. Employing our quantitative analysis, an effective vertical transport mass of m*/m₀ (MoS₂) ≈ 0.18 and m*/m₀ (WSe₂) ≈ 0.14 has been extracted for the first time and barriers at the metal contact-to-TMD interface of heights similar to those extracted for lateral transport in TMD transistors have been confirmed.