بررسي ترابرد كوانتومي الكتريكي در نانو ساختارهاي با پايه ي سيليسين

چكيده انگليسي :

Study of the Electronic antum Transport of Silicene Based Nanostructures Zahra Aslani zahra aslani@ph iut ac ir 02 09 2014 Department of physics Isfahan University of Te nology Isfahan 84156 83111 IranDegree M Sc Language PersianSupervisor Dr Farhad Fazileh fazileh@cc iut ac irAbstractSilicene as the counterpart of graphene for silicon with slightly bu led honeycomb geome try has been synthesized through epitaxial growth is novel two dimensional material hasa racted considerable a ention both theoretically and experimentally recently due to exoticelectronic structure and promising applications in nanoelectronics as well as compatibility withcurrent silicon based electronic te nology In recent years semiconductor nanostructures havebeen converted to the model systems for investigation of electrical conduction on short lengthscales e theorical framework commonly used to describe transport through nanoscopic de vices is the Landauer Bu iker formalism In this approa current through a conductor is ex pressed in terms of the possibility that an electron can transmit through it To simplify thediscussion we assume that the temperature is set to zero and transport is phase coherent Weconsider a zigzag silicene nanoribbon divided into three regions the device region the le and right lead that local structural disorders and edge defects can a ect the electronic trans port properties of this nanoribbons Additionally the bu led structure of silicene enables usto apply external electric eld and as a result can control bad gap in a wide range of energy insilicene In this project we provid systematic investigation on the electron transport propertiesof silicene nanoribbons in the presence of an external electric eld edge defects like vacanciesand disorders Anderson disorder We use the tight binding model to describe the hamiltony ofsilicene system en introduce the concept of Green s function and then show that a conductorconnected to in nite leads can be replaced by a nite conductor with the e ect of the leads incor porated through a self energy fuction is provides a convenient method for evaluating theGreen s fuctionn and henece the transmission function numerically A numerical te nique for calculating the transmission coe cients through a coherent mesoscopic conductor using it sGreen s function is introduced Furthermore we study the in uence of the electric eld on theband structure total and local density of states in silicene nanoribbons e results show jumpsor steps in the conductance of zigzag silicene nanoribbons versus energy e band structureobtained in this nanoribbons fully correspond to the diagrams of electrical conductivity Weshow that the band structure can be controlled by applying an electric eld perpendicular tothe silicene sheet In particular the gap decreases linearly to zero at a certain critical electric eld and then increases linearly Moreover the results show that disorders like vacancies anddisorder that is modeled with Anderson model lead to lower conductivity in zigzag silicenenanoribbons e edge states of the zigzag silicene nanoribbons are resistant to the disorders and in fact this disorder has no e ect on the conductance of the nanoribbons around the Fermienergy Keywords Electronic transport Zigzag silicene nanoribbon Green s function Tight bindingmodel disorder

اصلاني، زهرا

بررسي ترابرد كوانتومي الكتريكي در نانو ساختارهاي با پايه ي سيليسين

نانو نوارهاي سيليسيني زيگزاگ , تابع گرين , مدل تنگابست , بي نظمي