We report on the electrical characterisation of a series of thin amorphous chromium oxide (CrOx) films, grown by dc sputtering, to evaluate their suitability for use as on-chip resistors in nanoelectronics. By increasing the level of oxygen doping, the room-temperature sheet resistance of the CrOx films was varied from 28 Ω/ to 32.6 kΩ/. The variation in resistance with cooling to 4.2 K in liquid helium was investigated; the sheet resistance at 4.2 K varied with composition from 65 Ω/ to above 20 GΩ/. All of the films measured displayed linear current–voltage characteristics at all measured temperatures. For on-chip devices for quantum phase-slip measurements using niobium–silicon nanowires, interfaces between niobium–silicon and chromium oxide are required. We also characterised the contact resistance for one CrOx composition at an interface with niobium–silicon. We found that a gold intermediate layer is favourable: the specific contact resistivity of chromium-oxide-to-gold interfaces was 0.14 mΩcm2, much lower than the value for direct CrOx to niobium–silicon contact. We conclude that these chromium oxide films are suitable for use in nanoscale circuits as high-value resistors, with resistivity tunable by oxygen content.

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