Accurate Extraction of Schottky Barrier Height and Universality of Fermi Level De-pinning of van der Waals Contacts

Abstract

Due to Fermi level pinning (FLP), metal-semiconductor contact interfaces result in a Schottky barrier height (SBH), which is usually difficult to tune. This makes it challenging to efficiently inject both electrons and holes using the same metal - an essential requirement for several applications, including light-emitting devices and complementary logic. Interestingly, modulating the SBH in the Schottky-Mott limit of de-pinned van der Waals (vdW) contacts becomes possible. However, accurate extraction of the SBH is essential to exploit such contacts to their full potential. In this work, we propose a simple technique to accurately estimate the SBH at the vdW contact interfaces by circumventing several ambiguities associated with SBH extraction. Using this technique on several vdW contacts, including metallic 2H-TaSe${}_2$, semi-metallic graphene, and degenerately doped semiconducting SnSe${}_2$, we demonstrate that vdW contacts exhibit a universal de-pinned nature. Superior ambipolar carrier injection properties of vdW contacts are demonstrated (with Au contact as a reference) in two applications, namely, (a) pulsed electroluminescence from monolayer WS${}_2$ using few-layer graphene (FLG) contact, and (b) efficient carrier injection to WS${}_2$ and WSe${}_2$ channels in both nFET and pFET modes using 2H-TaSe${}_2$ contact.

References in corpus (3)

• High Mobility WSe2 p- and n-Type Field Effect Transistors Contacted by Highly Doped Graphene for Low-Resistance Contacts
• Low Resistance Metal Contacts to MoS2 Devices with Nickel-Etched-Graphene Electrodes
• High-Q Tantalum Oxide Nanomechanical Resonators by Laser-Oxidation of TaSe2

Cited by in corpus (1)

• Trion-trion annihilation in monolayer WS${}_2$