Length Dependence thermal conductivity of Zinc-Selenide (ZnSe) and Zinc Telluride (ZnTe)- A combined first principles and Frequency Domain Thermoreflectance (FDTR) study

TL;DR

This study combines first-principles calculations and FDTR measurements to analyze how the thermal conductivity of ZnSe and ZnTe decreases significantly at nanometer length scales, informing thermoelectric material design.

Contribution

It provides the first detailed analysis of length-dependent thermal conductivity of ZnSe and ZnTe using both computational and experimental methods.

Findings

Thermal conductivity of ZnSe decreases from 11.3 to 1.75 W/mK as length scales shrink from 10 nm to 10 nm.

Thermal conductivity of ZnTe decreases from 10 to 1.2 W/mK over the same length scale range.

Good agreement between first-principles calculations and FDTR measurements for bulk ZnSe and ZnTe.

Abstract

In this study, we report the length dependence of thermal conductivity (k) of zinc-blende Zinc-Selenide (ZnSe) and Zinc Telluride (ZnTe) for length scales between 10 nm and 10000 nm using first-principles computations based on density-functional theory. k value of ZnSe is computed to decrease significantly from 11.3 W/mK to 1.75 W/mK as the length scale is diminished from 10 nm to 10 nm. k value of ZnTe is also observed to decrease from 10 W/mK to 1.2 W/mK for the same decrease in length. We also measure the k of bulk ZnSe and ZnTe using Frequency Domain Thermoreflectance (FDTR) technique and observed a good agreement between FDTR measurements and first principles calculations for the bulk ZnSe and ZnTe. Understanding of thermal conductivity reduction at nanometer length scales provides an avenue to incorporate nanostructured ZnSe and ZnTe for thermoelectric applications.