Does P-type Ohmic Contact Exist in WSe2-metal Interfaces?

TL;DR

This study uses ab initio calculations and quantum transport simulations to analyze metal-WSe2 interfaces, revealing conditions under which p-type Ohmic contacts can form, especially with Pt and SOC effects.

Contribution

It provides the first comparative theoretical analysis of interfacial properties between WSe2 and various metals, highlighting the role of SOC in forming p-type Ohmic contacts.

Findings

Pt contact becomes p-type Ohmic with SOC inclusion.

SOC reduces hole Schottky barrier height.

Interlayer coupling affects barrier heights and polarity.

Abstract

Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of 2D WSe2 devices. We present the first comparative study of the interfacial properties between ML/BL WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, Pd contact has the smallest hole SBH with a value no less than 0.22 eV. Dramatically, Pt contact surpasses Pd contact and becomes p-type Ohmic or quasi-Ohmic contact with inclusion of the SOC. Our study provides a theoretical foundation for the selection of favorable metal electrodes in ML/BL WSe2 devices.