Thermal Transport in γ-InSe: Bulk Single Crystals and Thin Flakes

Published

May 5, 2026

Author(s)

Farjana Ferdous Tonni, Maliha Maliat, Md Sabbir Akhanda, Harsh Chandra, Ethan Scott, Abir Hasan, Sergiy Krylyuk, Nikhil Shukla, Costel Constantin, Patrick Hopkins, Junichiro Shiomi, Albert Davydov, Mona Zebarjadi

Abstract

We measure the temperature-dependent in-plane thermal conductivity, jkðTÞ, of high-purity c-InSe bulk single crystals and exfoliated thin flakes (30–50 nm) from 50 to 300 K. Our bulk results agree with prior bulk reports and provide a reproducible reference for phonon transport. In the literature, cross-plane thermal conductivity of supported InSe flakes shows relatively modest variation, whereas reported roomtemperature in-plane values for supported flakes span a wide range, including outliers that exceed bulk despite much smaller thickness. In our measurements, the flake jk at room temperature is lower than bulk, as expected, but exhibits substantial sample-to-sample variability; despite being thinner, intrinsic flakes show higher jk than doped flakes, consistent with reduced impurity scattering and improved flake uniformity. We analyze our data using a Callaway-type phonon-scattering model in which substrate interactions (including plausible strain-related renormalization of acoustic parameters) contribute to the observed spread near room temperature. However, below �150 K, the measured trends cannot be captured without invoking changes in sound velocity far larger than realistic strain levels, indicating that additional mechanisms beyond simple strain renormalization are required at low temperature. These measurements provide lowtemperature jk benchmarks for c-InSe flakes and constrain how much of the reported room-temperature spread can be explained by thickness, nonuniformity, and substrate effects alone.

Citation

Applied Physics Letters

Volume

128

Pub Type

Journals

Download Paper

https://doi.org/10.1063/5.0324196

Local Download

Keywords

InSe, thermal conductivity

Citation

Tonni, F. , Maliat, M. , Akhanda, M. , Chandra, H. , Scott, E. , Hasan, A. , Krylyuk, S. , Shukla, N. , Constantin, C. , Hopkins, P. , Shiomi, J. , Davydov, A. and Zebarjadi, M. (2026), Thermal Transport in γ-InSe: Bulk Single Crystals and Thin Flakes, Applied Physics Letters, [online], https://doi.org/10.1063/5.0324196, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=961105 (Accessed May 6, 2026)

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