Top-down fabricated ZnO nanowire transistors for application in biosensors

Top-down ZnO nanowire FETs have been fabricated using mature photolithography, ZnO atomic layer deposition (ALD) and plasma etching. This paper investigates the effects of oxygen adsorption by measuring FET characteristics at different gate bias sweep rates and by characterizing hysteresis effects. Unpassivated devices exhibit a low threshold voltage shift of 5.4 V when the gate bias sweep rate is varied from 2500 V/s to 1.2 V/s and a low hysteresis width of less than 1.5 V. These results are considerably better than the state of the art for bottom-up as-fabricated ZnO nanowire FETs and demonstrate the suitability of this top-down technology for biosensor applications.