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Title: Theory and modelling of single-electronic systems
Author: Babikir, Sharief Fadul
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1993
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In this thesis a theoretical study is made of the behaviour of single- electronic devices and systems. It is argued that the properties of single- electronic systems can be determined if the densities of the legal soliton states are known. The dynamics of the tunnelling electrons in such systems are modelled as a traffic process. An exact analytical technique based on the conventional Traffic Theory is formulated in the thesis. This new technique is compared with the traditional Monte-Carlo method and is shown to be superior, both in accuracy and speed. An algorithm that correctly and efficiently determines the set of active soliton states and the relationship between the states is also described. Tunnelling dynamics in a double-junction system are modelled as a Birth-Death process and an exact analytical solution is obtained. The model is then used to study the effects of discrete energy spectrum at the central dot of a double-junction system. A numerical solution for the Fokker-Planck like equation of the charge density function in a single tunnel junction circuit is implemented and used to study the coherence of the single-electron tunnelling (SET) oscillations. To avoid the heavy computations involved in the numerical solution a simple technique based on the distribution of the time between successive tunnel events is presented. It is shown that the SET oscillations do exist but the predicted ensemble average oscillations damp out exponentially with time. The regimes of operation of the double-junction system, the turnstile, are investigated. It is argued that the addition of resistive components to the circuit will enhance the reliability of the device and dramatically reduce the probability of unwanted events at the cost of reduced clocking rate. The Master-Equation formalism is extended to the double-junction system. The charge fluctuations are shown to be less than the fluctuations in a single-junction case. The processes degrading the reliability of single-electronic systems are studied. These include thermal and quantum fluctuations, the charge macroscopic quantum tunnelling and single charges that are being momentarily or permanently trapped in the vicinity of the system's electrodes. The Traffic model is extended to include these processes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available