Transport and Piezoresistive Characteristics of Ruthenium‐Doped Bismuth–Borosilicate Glass Thin Films Grown by Pulsed Laser Deposition

Ruthenium-doped bismuth–borosilicate glass thin films were grown by pulsed laser deposition as a material with a chemical structure equivalent to that of the functional region in a thick-film resistor (TFR) with piezoresistivity. X-ray diffraction and electron energy-loss spectroscopy analyses indicated that the thin films were in amorphous and contained both trivalent and tetravalent states of ruthenium after annealing in air. Analyses of transport properties verified that the electrical conduction in the film was via variable range hopping with a hole carrier. Furthermore, one of the films exhibits piezoresistive sensitivity six times as that of the TFR; the sensitivity has a strong correlation with the spatial extension of the wave function in the localized electronic states.