Electrically stable nanocomposite thin films formed by oxidation of Pt-ZrB2 nanolaminate templates

Platinum films of thickness <100 nm undergo agglomeration at temperatures exceeding 700 °C and lose electrically conductive pathways, making them unsuitable as stable films in high temperature electronic devices. To prevent agglomeration and create films that remain conductive above 1000 °C, a series of nanolaminate Pt-ZrB2 films comprised of Pt and ZrB2 were deposited to a total thickness of 200 nm at ambient temperature onto sapphire substrates using e-beam coevaporation. Annealing the nanolaminate films above 700 °C in air causes the ZrB2 and Pt layers to intermix, resulting in a nanocomposite Pt-ZrB2 film architecture. At temperatures between 1000 and 1300 °C in air, both monoclinic and tetragonal ZrO2 nanocrystallites are formed as indicated by x-ray diffraction, and they serve to hinder agglomeration of the Pt phase and allow for a stable network of conductive Pt-rich grains. Film electrical conductivity measurements acquired with a four-point probe indicate that the Pt-ZrB2 nanocomposite films reta...