| Summary: | 碩士 === 國立清華大學 === 動力機械工程學系 === 104 === Two-dimensional materials not only possess distinctive electrical and thermal conductivities, optical and mechanical properties, but also incline to be integrated with device manufacturing process. Therefore, it is regarded as a promising material to replace silicon materials.
Phosphorene, a novel two-dimensional puckered honeycomb lattice of phosphorus, possesses some remarkable electrical and optical properties, such as it has a direct bandgap, relatively high carrier mobility and on/off ratio, thereby making it to be a rising star among the electronics device materials. However, when applied in electronic devices, the phosphorene-based nano-scale electronic components often suffer from high temperature loading, which would change the physical properties of phosphorene and so affect the electrical performance. Well grasp of the thermodynamic and thermo-mechanical properties of phosphorene is crucial for successful implementation of the nano-scale electronic components. Besides, due to the limitation of fabrication technologies nowadays, atomistic defects are often perceived in phosphorene during the manufacturing process and affect the electrical and mechanical properties. Thus, the second goal of the study is to perform a systematic investigation of the effects of atomistic defects on the thermodynamic and thermo-mechanical properties of phosphorene.
Because of the distinct size-dependent quantum effects together with nanosize and single crystal structure, low-dimensional structures are potential for use in nano-scale electronic or electromechanical devices. Hence, converting two-dimensional sheet to one-dimensional structure, such as nanotubes, nanowires or nanoribbons and investigate their physical properties are necessary.
The work attempts to assess the thermodynamic and thermo-mechanical properties of phosphorene at constant temperature though the canonical ensemble MD model using a Nosé-Hoover Langevin (NHL) thermostat, including Young’s modulus, (Poisson’s ratio), shear modulus, specific heat and linear coefficient of thermal expansion. In addition, the defect effects of phosphorene is also examined. The thermodynamic and thermo-mechanical properties of phosphorene nanotubes of zigzag, armchair and hybrid type are investigated as well. The simulation results are compared with the literature data to demonstrate the validity of the proposed simulation model. In closing, the present work can be beneficial to the design and development of phosphorene-based nano-scale electronic components in future.
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