Enhancing Thermoelectric Efficiency in CrSi₂ Films through Al Ion Implantation-Induced Energy Filtering

This article reports the effects of Al ion implantation and thermal history on the microstructure and thermoelectric properties of amorphous CrSi2 thin films. Approximately 270 nm thick CrSi2 films were produced by magnetron sputtering and deposited onto a SiO2/Si substrate. Samples were then implanted with Al ions to achieve a concentration-depth plateau of about 1 at. % along the film thickness. The implantations were performed at room temperature or 250 °C. Postimplantation thermal annealing processes were performed for 1 h at 250 °C. This study shows that the electrical transport properties were significantly affected in the case of the formation of nanocrystallites, showing increased electrical resistivity and Seebeck coefficient compared to the reference. The results were attributed to an energy filtering effect caused by interfaces and boundaries stemming from a dense array of crystallites, blocking low-energy charge carriers and resulting in a significant gain in the Seebeck coefficient and power factor.