Schottky barrier and contact resistance of InSb nanowire field effect transistors

TL;DR

This study investigates the electrical contact properties of InSb nanowire FETs with Ti/Au contacts, revealing a gate-tunable Schottky barrier of about 20 meV and magnetic field-dependent contact resistance, informing future nanoelectronic device design.

Contribution

It provides the first detailed experimental analysis of Schottky barriers and contact resistance behavior in InSb nanowire FETs with Ti/Au contacts, including magnetic field effects.

Findings

Schottky barrier height of ~20 meV at metal-InSb NW interface

Contact resistance increases with magnetic field after a threshold

Magnetic depopulation of subbands explains resistance behavior

Abstract

Understanding of the electrical contact properties of semiconductor nanowire (NW) field effect transistors (FETs) plays a crucial role in employing semiconducting NWs as building blocks for future nanoelectronic devices and in the study of fundamental physics problems. Here, we report on a study of the contact properties of Ti/Au, a widely used contact metal combination, to individual InSb NWs via both two-probe and four-probe transport measurements. We show that a Schottky barrier of height $\Phi_{\rm{SB}}\sim20\ \rm{meV}$ is present at the metal-InSb NW interfaces and its effective height is gate tunable. The contact resistance ($R_{\rm{c}}$) in the InSb NWFETs is also analyzed by magnetotransport measurements at low temperatures. It is found that $R_{\rm{c}}$ at on-state exhibits a pronounced magnetic field dependent feature, namely it is increased strongly with increasing magnetic field after an onset field $B_{\rm{c}}$. A qualitative picture that takes into account magnetic depopulation of subbands in the NWs is provided to explain the observation. Our results provide a solid experimental evidence for the presence of a Schottky barrier at Ti/Au-InSb NW interfaces and can be used as a basis for design and fabrication of novel InSb NW based nanoelectronic devices and quantum devices.