Atomistic Study of the Electronic Contact Resistivity Between the Half-Heusler Alloys (HfCoSb, HfZrCoSb, HfZrNiSn) and the Metal Ag

TL;DR

This study uses atomistic ab initio calculations to analyze the structural and electronic properties of metal-HH alloy contacts, revealing how termination affects contact resistivity and providing quantitative resistivity values for thermoelectric applications.

Contribution

It provides detailed atomistic insights into the contact resistivity of Half-Heusler alloys with silver, highlighting the importance of surface termination and doping type.

Findings

p-type materials form ohmic contacts

n-type materials exhibit small Schottky barriers

calculated contact resistivity values set lower limits

Abstract

Half-Heusler(HH) alloys have shown promising thermoelectric properties in the medium and high temperature range. To harness these material properties for thermoelectric applications, it is important to realize electrical contacts with low electrical contact resistivity. However, little is known about the detailed structural and electronic properties of such contacts, and the expected values of contact resistivity. Here, we employ atomistic ab initio calculations to study electrical contacts in a subclass of HH alloys consisting of the compounds HfCoSb, HfZrCoSb, and HfZrNiSn. By using Ag as a prototypical metal, we show that the termination of the HH material critically determines the presence or absence of strong deformations at the interface. Our study includes contacts to doped materials, and the results indicate that the p-type materials generally form ohmic contacts while the n-type materials have a small Schottky barrier. We calculate the temperature dependence of the contact resistivity in the low to medium temperature range and provide quantitative values that set lower limits for these systems.