Controllable Schottky Barriers between MoS2 and Permalloy

TL;DR

This paper explores how to control Schottky barriers between MoS2 and permalloy contacts, enabling improved electronic and spintronic device performance through tunable contact properties.

Contribution

It demonstrates the development of ohmic contacts with negative Schottky barriers and tunable barrier heights using gate voltage and dielectric layers.

Findings

Achieved ohmic contact with multilayer MoS2 and permalloy with negative Schottky barrier.

Demonstrated tunability of Schottky barrier height down to zero.

High field-effect mobility exceeding 55 cm2V-1s-1 at low temperature.

Abstract

MoS2 is a layered two-dimensional material with strong spin-orbit coupling and long spin lifetime, which is promising for electronic and spintronic applications. However, because of its large band gap and small electron affinity, a considerable Schottky barrier exists between MoS2 and contact metal, hindering the further study of spin transport and spin injection in MoS2. Although substantial progress has been made in improving device performance, the existence of metal-semiconductor Schottky barrier has not yet been fully understood. Here, we investigate permalloy (Py) contacts to both multilayer and monolayer MoS2. Ohmic contact is developed between multilayer MoS2 and Py electrodes with a negative Schottky barrier, which yields a high field-effect mobility exceeding 55 cm2V-1s-1 at low temperature. Further, by applying back gate voltage and inserting different thickness of Al2O3 layer between the metal and monolayer MoS2, we have achieved a good tunability of the Schottky barrier height (down to zero). These results are important in improving the performance of MoS2 transistor devices; and it may pave the way to realize spin transport and spin injection in MoS2.