Fabrication and characterization of hybrid single electron devices

Nowadays DC current metrology is not yet supported by quantum based standards, intrinsically standard that does not require calibration depending only by fundamental constants. This thesis is focused on the modeling and realization of nano-devices for potential applications in DC current metrology. The choice of the fabrication technique is a crucial step for these tricky processes. Two kind of processes have been optimized at INRiM, the first being the most investigated from the 80s, the second being a recently purposed mesoscopic tunnel junction hybrid assembly nanofabrication technique concerning the Focused gallium Ion Beam (FIB) present at Nanofacility Piemonte. The main objective of our experimental activity is to compare the fabrication and characterization competences acquired at INRiM regarding a well documented device, trying , subsequently, to transfer them to a more innovative solution. The first introductory chapter starts with an overview of the so-called metrological triangle binding together volt, ohm and ampere in a fundamental definition of this three SI units; it follows a representative selection of candidate devices for the new definition of the ampere together with a short description of the physics that lies behind them. The second chapter is a detailed presentation of our Hybrid Single Electron Transistor theoretical modeling; its applications in DC current metrology are deeply threated focusing on the intrinsic and technological factors that limit the ultimate reachable accuracy of the presented device. The third chapter is a technical discussion of the two processes we used to fabricate our single electron devices. The first part is a review of our slightly modified version of the quite famous Dolan technique; the second sections is a detailed description of physical and technological principles, foundations for the innovative FIB process. The last chapter presents a set of electrical measurements devoted to a better understanding of our fabrication and characterization processes quality and reproducibility in relation to the well documented single-electronics literature. In appendix a collection of process recipes and instrumentation technical descriptions is present.