The thinner the cooler: a study on thermal transport properties of platinum diselenide

by Virginia Greco

The thermal dissipation in new ultra-thin materials is extremely relevant for heat management of future electronic devices. A combination of characterization techniques allows studying how this and other properties vary as a consequence of increased thickness and change of crystallinity of the material.

Thin films of semiconductor materials, made of just one or a few atomic layers, are very attractive for the microelectronics industry. They exhibit peculiar optical, electronic and thermal properties deriving from their reduced thickness, which are much different from those of the corresponding bulk materials.

Among them, thermal conductivity is particularly important, since integrated circuits and micro- and nano-scale devices tend to heat up, resulting in poor performance or even damage. The ability of these “bidimensional” (2D) materials to dissipate heat, and thus cool down, is crucial to their application and is being extensively studied by materials scientists.

The ICN2 Phononic and Photonic Nanostructures Group, led by ICREA Prof. Dr Clivia Sotomayor-Torres, has recently performed a study on the influence of the thickness and the crystallinity on the thermal properties of platinum diselenide (PtSe₂), a material of the metal dichalcogenide family. These materials exhibit outstanding properties which make them great candidates for integration in future high-performance ultra-thin devices. This work, published in 2D Materials and Applications, was coordinated by Dr Emigdio Chavez-Angel and Dr Alexandros El Sachat, from Prof. Sotomayor-Torres’ team, and developed in collaboration with researchers at the Université Grenoble Alpes (France) and at the University of California, Davis (US).

The authors used a combination of advanced characterization techniques to analyze the behaviour of platinum diselenide films of thickness varying between 1 and 40 layers. In fact, in a material composed of a stack of few layers of the same or different nature, heat normally “travels” in the vertical direction, across layers. Consequently, depending on the number of layers and the interactions between them, heat dissipation can vary significantly. The structure of the lattice (which can be mono- or multi-crystalline) also affects this and other properties of the material.

Thanks to these characterization techniques, the researchers were able to describe the behaviour of their material and to observe a reduction of the cross-plane thermal conductivity over 20 layers, especially in polycrystalline structures. The results of this study offer insight into the heat transport and other phenomena taking place in metal dichalcogenides and enhance our knowledge of 2D materials with potential implication for the design of future energy-saving ultra-thin electronic devices.

Reference article:

Alexandros El Sachat, Peng Xiao, Davide Donadio, Frédéric Bonell, Marianna Sledzinska, Alain Marty, Céline Vergnaud, Hervé Boukari, Matthieu Jamet, Guillermo Arregui, Zekun Chen, Francesc Alzina, Clivia M. Sotomayor Torres & Emigdio Chavez-Angel, Effect of crystallinity and thickness on thermal transport in layered PtSe2. npj 2D Materials and Applications 6, 32 (2022). DOI: 10.1038/s41699-022-00311-x