Electron-phonon Interaction. Nanosystems

Hot-electron effect is one of the frontier of condensed matter physics. Nanotubes is a very wide range of structures, they have unique mechanical, optical and electrical properties, the reseach of hot-electron in nanotubes is important for deeper understand it's properties and application. In this paper, a thin cylindrical shell is exploited to approximate nano-shells, the corresponding low energy local phonon density of states are analytically obtained, and apply the conclusion to carbon nanoshell.Nowadays, the size of integrated circuits and semiconductor electronic devices becomes more and more smaller, and the density of electronic components on unit chip is increase, so the reseach related to size effect is important as devices are reduced in size. In this paper, the temperature dependent resistivity of Cu and the mobility of silicon are calculated from first-principles.The main works in this paper are as follows:(1) Firstly, the electron-phonon scattering in thin cylindrical shell is discussed. In this model phonons are confined to quasi-one dimension but electrons behave three-dimensionally, the calculate results show the electron-phonon scattering rate in the shell is proportional to 3 power of the temperature. Currently, the primary theoretical results states that the rate of energy exchange from the electrons to the phonon is related to n power of the temperature, where n=D+2, and D is the dimension of phonons. Our results are according to the well kown conclusion.(2) We calculate the temperature dependent resistivity of copper based on first-principle method. It's found the resistivity of copper is increased when the size reduced due to size effect. In this paper we consider three different vibration modes to investigate the surface electron-phonon scattering contribution to the resistivity of Cu, the results show the surface electron-phonon scattering due to the enhanced resistivity of Cu films, and the resistivity values are non-linear with temperature. When we suppress the vibrations of surface atoms, we will get lower resistivity.(3) The mobility of different doped silicon are calculated in ballistic regime with our ab. initio way. in this paper, a giving doping is obtained by shifting the Fermi level from its intrinsic position toward the conduction band edge or valence band edge. Our calculation results show the mobility of N-type semiconductor is about 2 to 3 times to P-type due to the effective mass of electron lighter than the hole. Both electron and hole have their highest mobility in the<110> direction in silicon.