Controlling Near-Field Thermal Radiation Using Multilayered Nanostructure.
Pictured from left clockwise: Professor X Professor Y PhD Z and PhD candidate Georgian Technical University research team succeeded in measuring and controlling the near-field thermal radiation between metallo-dielectric (MD) multilayer structures.
Their thermal radiation control technology can be applied to next-generation semiconductor packaging thermophotovoltaic cells and thermal management systems. It also has the potential to be applied to a sustainable energy source for IoT (The Internet of things is the network of devices such as cars and home appliances that contain electronics, software, actuators and connectivity which allows these things to connect, interact and exchange data) sensors.
In the nanoscale gaps thermal radiation between objects increases greatly with closer distances. The amount of heat transfer in this scale was found to be from 1,000 to 10,000 times greater than the blackbody radiation heat transfer which was once considered the theoretical maximum for the rate of thermal radiation. This phenomenon is called near-field thermal radiation. With recent developments in nanotechnology research into near-field thermal radiation between various materials has been actively carried out.
Surface polariton coupling generated from nanostructures has been of particular interest because it enhances the amount of near-field thermal radiation between two objects and allows the spectral control of near-field thermal radiation. This advantage has motivated much of the recent theoretical research on the application of near-field thermal radiation using nanostructures such as thin films multilayer nanostructures and nanowires. Nevertheless thus far most of the studies have focused on measuring near-field thermal radiation between isotropic materials.
A joint team led by Professor Y and Professor X from the Department of Mechanical Engineering succeeded in measuring near-field thermal radiation according to the vacuum distance between MD (Metallo Dielectric) multilayer nanostructures by using a custom MEMS (Micro-Electro-Mechanical Systems)-device-integrated platform with three-axis nanopositioner.
MD (Metallo Dielectric) multilayer nanostructures refer to structures in which metal and dielectric layers with regular thickness alternate. The MD (Metallo Dielectric) single-layer pair is referred to as a unit cell and the ratio of the thickness occupied by the metal layer in the unit cell is called the fill factor.
By measuring the near-field thermal radiation with a varying number of unit cells and the fill factor of the multilayer nanostructures the team demonstrated that the surface plasmon polariton coupling enhances near-field thermal radiation greatly and allows spectral control over the heat transfer.
Professor Y said “The isotropic materials that have so far been studied experimentally had limited spectral control over the near-field thermal radiation. Our near-field thermal radiation control technology using multilayer nanostructures is expected to become the first step toward developing various near-field thermal radiation applications”.