Supporting data for Probing Phonon Mean-Free-Path Distribution via Thickness-Dependent Thermal Conductivity in Epitaxial SrSnO₃

This dataset reports thickness-dependent through-plane thermal conductivity measurements of ultra-wide-bandgap strontium stannate (SrSnO₃) thin films with thicknesses spanning 10–350 nm. The data were obtained using time-domain thermoreflectance (TDTR) on a series of epitaxial films grown by hybrid molecular beam epitaxy, enabling systematic isolation of size effects on thermal transport. In addition to experimental thermal conductivity values, the dataset includes reconstructed phonon mean-free-path (MFP) distributions derived directly from experimental thickness-dependent measurements using an integral MFP formalism. These reconstructions separate particle-like and wave-like contributions to thermal transport without invoking first-principles phonon dispersions or empirical scattering models.

The value of this dataset lies in providing an experimentally grounded phonon MFP spectrum for a strongly anharmonic perovskite semiconductor, offering a benchmark for validating thermal transport theories and modeling approaches in ultra-wide-bandgap oxides. By enabling direct comparison between nanoscale thermal conductivity suppression and underlying phonon length scales, the data support studies of structure–thermal property relationships relevant to device scaling. The dataset is released to promote transparency, reproducibility, and reuse in thermal transport modeling, nanoscale heat conduction research, and the design of UWBG electronic materials operating under strong size and thermal constraints.