Micro and Nanoscale thermal science - Characterization and measurement methods

Heat generation is a universal consequence of physical activity. Thermal management is therefore at the heart of all new technologies based on the acquisition and storage of information or energy. In this context, rapid advances in the synthesis and processing of materials with nanoscale structures have created a strong demand for a better scientific understanding of thermal transport in micro- and nanostructured devices and nanomaterials. The miniaturization of electronic and optoelectronic components and circuits, and the increased switching speeds of these components, have led to localized heating problems at micro- and nanoscales. Steady-state and transient characterization of temperature distribution in these systems and their interconnections at these same scales is therefore essential for pre-commercialization performance and reliability analysis.

Modern materials science and technology are increasingly focused on controlling matter at the nanoscale. By nanostructuring materials, their physical properties can be adjusted to achieve optimum performance. This is the case of nanomaterials used for renewable energy production (thermoelectric, photovoltaic), or structural composites. In addition, interfaces between materials are becoming increasingly important at small length scales. How can we characterize heat transfer within these systems, whose characteristic sizes are close to or less than the mean free path of energy carriers? The aim of this article is to answer this question.

Thermal management at micro and nano scales remains a major problem in many fields, particularly microelectronics. In particular, it requires access to measurement techniques and models compatible with the small physical dimensions of the system or material, as well as the required measurement accuracy. However, traditional measurement methods are becoming insufficiently sensitive or unsuitable for micro and nano scales, due to the limitations of the physics involved. In particular, the physical mechanisms of heat transfer may be completely different from those at the macroscopic scale.

These limitations are still the subject of fundamental and applied research today. This has led to the development of a wide variety of instruments, whether optical, with deposited resistive probes or scanning probes. The objectives of these instruments are to measure temperature on the submicron scale, and the thermal properties of thin films and nanomaterials.

The first part of this article will examine the limits of classical laws describing heat transfer mechanisms, and provide the conceptual and theoretical foundations needed to understand the current challenges of micro and nanothermics in various fields. The second part will focus on the general...