Probing Phonon-Dominated Transport in Sb₂Se₃ Thin Films

The need to route photonic signals and dynamically reconfigure devices for silicon photonic circuits has placed phase change Sb₂Se₃ at the forefront of optical materials research. This is largely due to Sb₂Se₃ displaying a large change in complex refractive index between crystalline and amorphous phases with no absorption losses (1-3). Surprisingly, the thermal properties of Sb₂Se₃ ­ thin films are not well known, despite their technological relevance. These thermal properties play a vital role in changing phases and are critical for the optimization of emerging photonic technology.

In this work, we uncover the thermal conductivity (k) and thermal interface characteristics of sputtered Sb₂Se₃ on silicon from 10-60 nm in thickness, revealing a roughly two-fold increase of k to ~0.40 W/m/K when taken to 290^oC for 60 nm films. Little change in k was found for 10 nm films in the same temperature range (~0.18-0.21 W/m/K). Electrical resistivity measurements suggests phonon-dominated transport, while resistive crossbar measurements (4,5) provide their electronic device behavior in an emerging computing platform. In summary, our detailed measurements reveal insights to accurately model and optimize photonic hardware based on the emerging material Sb₂Se₃.