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Vanadium oxide (VOx) thin films were deposited by reactive pulse dc magnetron sputtering process using a pure vanadium metal target. The structural, microstructure, and electrical properties were correlated as a function of processing parameters such as substrate temperature, Ar:O partial pressures ratios, and pulsed dc power to fabricate these films. The VOx films deposited at various substrate temperatures between 30 and 300°C using a range of oxygen to argon partial pressure ratios exhibited huge variation in their microstructure even though most of them are amorphous to x-ray diffraction technique. In addition, the electrical properties such as temperature coefficient of resistance (TCR), resistivity, and noise levels were influenced by film microstructure. The TCRs of the VOx films were in the range of −1.1%to−2.4%K−1 having resistivity values of 0.1–100Ωcm. In particular, films grown at lower substrate temperatures with higher oxygen partial pressures have shown finer columnar grain structure and ex...

Cathode hysteresis in the reactive pulsed dc sputtering of a vanadium metal target was investigated to correlate the structural and electrical properties of the resultant vanadium oxide thin films within the framework of Berg’s model [Berg et al., J. Vac. Sci. Technol. A 5, 202 (1987)]. The process hysteresis during reactive pulsed dc sputtering of a vanadium metal target was monitored by measuring the cathode (target) current under different total gas flow rates and oxygen-to-argon ratios for a power density of ∼6.6.W/cm2. Approximately 20%–25% hysteretic change in the cathode current was noticed between the metallic and oxidized states of the V-metal target. The extent of the hysteresis varied with changes in the mass flow of oxygen as predicted by Berg’s model. The corresponding microstructure of the films changed from columnar to equiaxed grain structure with increased oxygen flow rates. Micro-Raman spectroscopy indicates subtle changes in the film structure as a function of processing conditions. The...

By combining optical lithography and chemical self-assembly, the authors circumvent the limitations of photolithography and provide a parallel, low-cost alternative to fabricate sub-50nm features. Self-assembled multilayers, composed of alternating layers of α,ω-mercaptoalkanoic acids and copper (II) ions (“molecular rulers”), are used as an organic sidewall spacer resist on initial lithographic structures enabling the precise, proximal placement of a secondary structure via lift-off. Here, the authors implemented a positive-tone bilayer resist for improved line-edge characteristics of the secondary structure and evaluated the lithographic and electrical performance of nanostructures fabricated using this approach. Additionally, they describe extensions of this technique by which planar nanojunctions were created, and the generated nanometer-scale pattern was transferred to the underlying substrate.