Study On Macro Electron Shuttle Model Of Quantum Dot Electromechanical Devices

With the rapid progress of micro-and nano-fabrication technologies, the NanoElectromechanical Systems (NEMS) have become the inevitable developing trend of furtherminimizing Micro Electromechanical Systems (MEMS). NEMS not only has manyadvantages such as small volume, rapid response, high efficiency and low power consumption,but also possesses abundant quantum mechanical characteristics. As a result, the preparation,properties and applications of NEMS have become one of the most concerned research areasin recent years. Particularly, the quantum dot based nano electromechanical devices is one ofthe most important research directions of NEMS. Fabricating the quantum dot based nanoelectromechanical devices usually needs to preparing and locating quantum dots accurately. Inaddition, forming the high quality tunneling barrier accurately between the quantum dot andthe surroundings is the most difficult issue. Most current researches about quantum dot nanoelectromechanical devices are limited to several device structures as the cantilever, clampedbeam and molecular transistor, in which the accurate fabrication of suitable tunneling barrierremains an unsolved problem.Based on the fundamental theory models of the electromechanical single electrontransistor (EMSET), we propose a novel floating quantum dot electromechanical device, inwhich the charge transfer between the quantum dot and electrodes is by the new “directcontacting” method. In this device, the difficulty in fabricating the tunneling barrier can beavoided since the Coulomb island has the full mechanical freedom in the whole gap betweenthe source and drain electrodes. However, the premise of current semi-classical theory model,the moving range of Coulomb island being much smaller than the distance between the sourceand drain electrodes, cannot be satisfied anymore. Therefore, we design a macro electronshuttle corresponding to the floating quantum dot electromechanical device. Based on thein-depth investigation of this model device, we revise the existing semi-classical theory model,providing helpful theoretical and experimental guidance for the further study on quantum dotbased nano electromechanical devices.In this thesis, we analyze the working principle of floating quantum dotelectromechanical devices firstly. Then, we design and realize the macro electron shuttlemodel device successfully. The testing circuit is established according to the characteristics ofthe model device. The experiment results indicate that the characteristics of the macroelectron shuttle cannot be predicted by the existing semi-classical model. The difference isexplained theoretically based on the electric field simulation results obtained by the finiteelement analysis. The semi-classical theory model is improved by introducing a correction factor, and the range of the correction factor is determined based on experiment measurements.Furthermore, we extend the macro electron shuttle model device (the single-ball oscillator)and implement a new real random number generator based on the multi-ball oscillator.Aiming at the random characteristics of both amplitude and frequency of real time signals inthe multi-ball oscillator, we present two signal processing schemes to convert the electricalsignals to binary codes. The measured real time electrical signals are processed by using theMatlab program, and the feasibility of the signal processing schemes is verified finally.