Coulomb blockade effects in anodised niobium nanostructures

摘要: Niobium thin film nanostructures were fabricated using electron beam lithography and a liftoff process involving four layer resist system. Wires having micrometres in length below 200 nm width deposited on an insulating substrate subsequently thinned by anodisation. The resistance of the wires was monitored situ could be trimmed controlling anodisation voltage time. method appears appropriate for fabrication very small resistors use as biasing single devices. Transport properties these measured at millikelvin temperatures. They had nonlinear current-voltage characteristics around zero bias showed transistion from superconducting to behaviour. Analysis offset that Coulomb blockade set when sheet films exceeded quantum approx 6.45 kOhm. Samples transistor-like geometry with two variable thickness weak links made combined angular evaporation niobium Overlapping gate electrodes samples. drain-source modulated voltage, giving response typical system multiple ultrasmall tunnel junctions. thesis contains five page appendix recipes.