On the junction physics of Schottky contact of (10, 10) MX2 (MoS2, WS2) nanotube and (10, 10) carbon nanotube (CNT): an atomistic study

TL;DR

This study uses atomistic simulations to analyze the electronic and transport properties of MoS2 and WS2 nanotube-carbon nanotube junctions, revealing Schottky barrier formation and diode-like behavior relevant for nanoelectronics.

Contribution

It provides a detailed atomistic and quantum transport analysis of MX2 nanotube-CNT junctions, highlighting their potential in nanoelectronic applications.

Findings

Formation of inhomogeneous Schottky barriers with bias-dependent modulation

Calculated ideality factors of 1.1322 (MoS2) and 1.2526 (WS2)

Schottky barrier heights range from 0.697 to 0.664 eV (MoS2) and 0.669 to 0.610 eV (WS2)

Abstract

Armchair nanotubes of MoS2 and WS2 offer a sizeable band gap, with the advantage of a one dimensional (1D) electronic material, but free from edge roughness and thermodynamic instability of nanoribbons. Use of such semiconducting MX2 (MoS2, WS2) armchair nanotubes (NTs) in conjunction with metallic carbon nanotubes (CNT) could prove useful for nanoelectronics and photonics applications. In this work atomistic simulations of MoS2 NT-CNT and WS2 NT-CNT junctions are carried out to study the physics of such junctions. With density functional theory (DFT) we study the carrier density distribution, effective potential, electron difference density, electron localization function, electrostatic difference potential and projected local density of states of such MX2 NT-CNT 1D junctions. Thereafter the conductance of such a junction under moderate bias is studied with non-equilibrium Greens function (NEGF) method. From the forward bias characteristics simulated from NEGF, we extract diode parameters of the junction. The electrostatic simulations from DFT show the formation of an inhomogeneous Schottky barrier with a tendency towards charge transfer from metal and chalcogen atoms towards the C atoms. For low bias conditions, the ideality factor was calculated to be 1.1322 for MoS2 NT-CNT junction and 1.2526 for the WS2 NT-CNT junction. The Schottky barrier heights displayed significant bias dependent modulation and are calculated to be in the range 0.697 - 0.664eV for MoS2 NT-CNT and 0.669-0.610 eV for the WS2 NT-CNT respectively.