Electron Transport Effects Of Substitutional Atoms On Low-Dimensional Silicon And Carbon Nanomaterials

As the physical blocks of the integrated circuit, transistors have owned a nano-scale size with the development of modern technology. It is well known that materials in nano-scale will exhibit a series of fantastic properties, the researches on the nanometer electronic devices then become amazing. Though many efforts have been made in the materials used in nanometer electronic devices and the manufacture of nano-scale electronic devices, some critical problems still need to be solved, In this context the corresponding theoretical researches will give directions to the further development for this field.In this thesis, molecular dynamics and non-equilibrium Green function are employed to systematically investigate the electron transport properties of nanometer electronic devices, and the effect of substitutional impurities in the devices is especially studied. The electron transport properties of ultra-thin Si nanowire devices with substitutional impurities and the effects of the gate electrodes were studied. Moreover, a new nanometer electronic device model consisted of h-BN and C hybrid nanotube is established and systematically investigated. The main results of this thesis are given as follows.(1) The electron transport properties of Si-based nanowire device with various substitutional atoms located at different position are studied. The asymmetrical substitution of nanowires leads devices to exhibiting a nearly unidirectional conductivity. Pronounced negative differential resistance is observed, especially when the substitutional atoms are aggregated in the center region of the nanowire. Moreover, gate voltages can switch the device between on and off states by changing the energy levels of nanowires.(2) Due to the well structural compatibility and the different electrical properties, h-BN nanotube and carbon nanotube are selected to form the heterostructure electronic devices. It is found that the axial length of h-BN nanotube have a great impact on the electron transport probability strength, the current will nearly exponentially decrease with the increase of axial length of h-BN nanotube part. Moreover, when the device contain the inner carbon nanotube part, the transmission peaks will appear in the transmission spectra and be decided by the distribution of the inner carbon nanotube part.This study provides a deep understanding on the effect of substitutional atoms for nanometer electronic devices. And it will give a practical significance for the further high performance nanometer electronic devices.