High temperature coefficient of resistance and low noise tungsten oxide doped amorphous vanadium oxide thin films for microbolometer applications

• Published in: Thin solid films 2019-12, Vol.691, p.137590, Article 137590
• Main Authors: Celik, Ozer, Duman, Memed
• Format: Article
• Language: English
• Subjects: Amorphous vanadium tungsten oxide; Doped vanadium oxide; Low noise; Microbolometer; Reactive direct-current magnetron sputtering; Temperature coefficient of resistance; Thin films; Tungsten oxide
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2019.137590

•Sputtered WO3 doped VOx with high temperature coefficient of resistance (TCR) of 3.02%/K.•Resistivity and TCR variation were investigated with increasing O2 flow rate.•WO3 doped VOx thin film has low 1/f noise level similar to commercial VOx.•Characterization techniques showed that VWOx film is composed of VO2, V2O3 and V2O5. In this study, we report tungsten oxide (WO3) doped vanadium target in order to sputter amorphous vanadium tungsten oxide (a-VWOx) thin films by reactive direct-current magnetron sputtering technique. No post annealing and post oxidation steps were applied to improve bolometric properties. Thin films with high temperature coefficient of resistance, up to 3.02%/K, were prepared with resistivity range of 1–10 Ω cm thereby controlling the oxygen flow rate and sputtering conditions. Thin film composition was determined using X-ray photoelectron spectroscopy analysis which showed that the film has a mixed phase of V2O5, VO2 and V2O3. The noise level of the deposited film at 20 Hz was calculated as 1.9 × 10−15 V2/Hz from the noise spectrum density analysis. This noise level was found out to be comparable to the literature for VOx films deposited by ion beam deposition technique.