Reduced Thermal Conductivity in Silicon Thin-Films via Vacancies

Abstract

An experimental method is defined that reduces the thermal conductivity in Si films by ~90 % compared to control samples, while keeping the thermoelectric power factor almost unchanged. This is done by creating vacancy-rich films via high-energy self-implantation of Si, followed by rapid-thermal annealing. TCAD simulations suggest that this approach is scalable for application in thin-film thermoelectric generators, as an alternative to more expensive and less Earth-abundant materials such as bismuth telluride. This approach to Si thermoelectrics could be straight-forward for scale-up to thin-film device dimensions, something that is a major challenge for other methods used for Si thermal conductivity reduction.

Non-Equilibrium Thermodynamics of Heat Transport in Superlattices, Graded Systems, and Thermal Metamaterials with Defects

“…First, as a motivation and overview of the context, we have referred to defect engineering [80][81][82][83][84][85][86][87][88][89][90][91], dislocation engineering [1][2][3][4][5][6][7], stress engineering [92][93][94][95][96][97], phonon engineering [98][99][100][101][102], and nanoengineering, to see the several aims of these relatively new engineering techniques on which much current activity is focused. Second, we have examined the nonequilibrium thermodynamic context; using procedures of rational extended thermodynamics, we have derived in the anisotropic case the constitutive equations and the rate equations for charges and heat fluxes, obtaining a balanced system of equations to describe extrinsic semiconductors and superlattices with defects of dislocations.…”

“…Defect engineering aims at finding the particular effects of the different kinds of defects on the several transport coefficients or on many other aspects of the system, as for instance in activating molecules for autocatalytic or electrocatalytic reactions, by introducing highly active sites for chemisorption and absorption, or for improving the efficiency of photovoltaic solar cells [80][81][82][83][84][85][86][87][88][89][90][91].…”

Positron probing of disordered regions in neutron‐irradiated silicon

“…It has been demonstrated recently that the thermal conductivity of Si thermoelectric generators may be reduced by ∼90% by creating vacancy‐rich films. As a temperature difference across the module plays a key role in the thermoelectric performance, information about the microstructure of the open vacancy volume of defects in these films is of great importance.…”