Sputtering Grown Wide Band Gap AlN Thin Films for High Power Capacitors

This paper reports on the characterization of optical and electrical properties of aluminum nitride (AlN) thin films, achieved by varying the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$N_{2}/Ar$</tex> gas ratio during the sputtering process. Our findings reveal that AlN thin films can attain superior optical transmission in the visible spectrum compared to glass substrates, particularly at an optimal <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$N_{2}/Ar$</tex> ratio. Additionally, we observed that the dielectric strength and breakdown voltage of the films improve as the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$N_{2}/Ar$</tex> ratio decreases, reaching a dielectric strength of approximately 4.5× 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> V/mm under optimized conditions. The study also demonstrates an increase in capacitance with higher applied DC voltage, attributed to the piezoelectric properties of AlN. These results highlight the potential of AlN thin films for applications in dielectric layers for power capacitors and gate materials in thin-film transistors.