各種高科技產業的快速發展和微機電製程技術的快速進步，使材料結構的尺度和元件製程的精確度已經邁入奈米尺度(nanoscale)的操控世界。本研究重點在於探討磷化鎵奈米線在奈米尺度下閃鋅礦與纖鋅礦結構之機械及材料特性。在理論模擬方法上，使用分子動力學模擬法與Tersoff勢能函數作為理論基礎，並配合軟體LAMMPS作為工具，分析在不同的結構、方向、長度、溫度、截面尺寸及形狀等條件下之磷化鎵奈米線受單軸向拉伸，材料的滑移系統、強度、應力分佈以及奈米線在拉伸的斷裂過程。其結果顯示不同方向之閃鋅礦結構奈米線中，楊氏模數的大小為[111]>[110]>[001]。而閃鋅礦[111]與纖鋅礦[0001]奈米線在不同截面形狀下則是以方形截面會優於六邊形截面；而從奈米線截面尺寸來看，發現閃鋅礦[111]方向之奈米線其強度與破壞應力隨著截面直徑增加而上升；纖鋅礦[0001]方向則是隨著直徑增加而先生後降。以六邊形截面之閃鋅礦[111]與纖鋅礦[0001]奈米線來看，奈米線之破壞應力會隨著溫度降低、應變速率下降以及長度增加而升高，此外，從奈米線拉伸過程可觀察出，閃鋅礦結構在破壞時是由「角」開始，而纖鋅礦結構在破壞時是由「邊」開始。纖鋅礦結構之奈米線無論是強度及楊氏模數都優於閃鋅礦結構之奈米線。

Mechanical and fracture behaviors of GaP nanowires (NWs) in zinc-blende and wurtzite phases were investigated by Molecular dynamics simulations using the program package LAMMPS with Tersoff potential. Simulation was performed and focused on the effects of different structure, orientation, length, temperature and diameter on the behaviors of slip system, strength, stress distribution and fracture process of NWs under uniaxial tension. The results show that the magnitude of Young’s modulus of zinc-blende GaP NWs in [111] orientation is greater than [110] and [001], while [001] is the smallest. For zinc-blende [111] and wurtzite [0001] GaP NWs with different cross-sectional shape, the magnitude of Young’s modulus of square is higher than the hexagon. On the other hand, size effect of the NWs is significant. The magnitude of Young’s modulus and fracture stress of zinc-blende GaP nanowires decreases with the decrease of diameter. However, the magnitude of Young’s modulus and fracture stress of wurtzite GaP nanowires has no such a monotonic relation. In addition, the fracture stress of both zinc-blende and wurtzite GaP NWs increases with decreasing temperature and strain rate and with increasing length of NWs. Viewing from the cross-section, the fracture of zinc-blende and wurtzite GaP NWs individually initiates from the corner and the side of the outer surface. Specially, the strength of the NWs in wurtzite structure is higher than in zinc-blende structure.

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