Thermal conductivity reduction due to phonon geometrical scattering in nano-engineered epitaxial germanium

• DOI: 10.1063/5.0204222
• Publication Date: 2024-05-07T22:04:17Z
• Authors: Jessy Paterson; Sunanda Mitra; Yanqing Liu; Mustapha Boukhari; Dhruv Singhal; David Lacroix; Emmanuel Hadji; André Barski; Dimitri Tainoff; Olivier Bourgeois
• Keywords: Condensed Matter - Mesoscale and Nanoscale Physics; Mesoscale and Nanoscale Physics (cond-mat.mes-hall); FOS: Physical sciences; 02 engineering and technology; 0210 nano-technology; 530; [PHYS.COND.CM-MSQHE]Physics [physics]/Condensed Matter [cond-mat]/Mesoscopic Systems and Quantum Hall Effect [cond-mat.mes-hall]; 620

Nano-engineering crystalline materials can be used to tailor their thermal properties. By adding new nanoscale phonon scattering centers and controlling their size, one can effectively decrease the phonon mean free path, hence the thermal conductivity of a fully crystalline material. In this Letter, we use the 3ω method in the temperature range of 100–300 K to experimentally report on the more than threefold reduction of the thermal conductivity of an epitaxially grown crystalline germanium thin film with embedded polydispersed crystalline Ge3Mn5 nano-inclusions with diameters ranging from 5 to 25 nm. A detailed analysis of the structure of the thin film coupled with Monte Carlo simulations of phonon transport highlights the role of the nano-inclusions volume fraction in the reduction of the phononic contribution to the thermal conductivity, in particular its temperature dependence, leading to a phonon mean free path that is set by geometrical constraints.