摘要:
在紧束缚理论的基础上,推导出轴向拉伸和扭转形变时碳纳米管(CNT)的能带公式.结果显示拉伸和扭转形变都可以改变CNT的导电性质,在金属型和半导体型之间转变,特别是对于锯齿型CNT,根据n与3的余数关系,在拉伸和扭转中分别显示出三种不同的变化规律.进一步应用场效应晶体管Natori理论模拟计算形变对cNT场效应晶体管的电流.电压特性的影响,锯齿型CNT根据n与3的余数关系表现出不同的电流变化趋势,而对于扶手椅型CNT轴向拉伸不改变电流;在扭转形变时,CNT电流急剧升高,特别是扶手椅型CNT.锯齿型CNT和扶手椅型CNT的电流随扭转角度和外电压行为明显不同.在某些特定的扭转角度,电流随扭转角度变化非常显著,显示出锯齿型CNT和扶手椅型CNT发生半导体型与金属型之间的转变.
Abstract:
On the basis of the tight-binding theory, we derive the band structure formula of the deformed carbon nanotube. The results show that the band gap varies with increasing deformation, which shows that the deformation can change the nature of the conductivity of carbon between the metal-type and semiconductor-type. Especially for zigzag nanotubes, there are three different rules goveoning this translation, which is dependent on the remainder of n divided by 3. Furthermore, by using Natori theory on the field-effect transistor we study the current-voltage characteristics of deformed carbon nanotube field-effect transistors. For strain deformation, the conductivity of zigzag nanotube presents different characteristics with the remainder of n by 3. For armchair nanotubes, the conductivity does not change with the strain parameter. However, for torsion deformation, the conductivity rapidly increases, specially for the armchair tube. It has many obviously different conductivity behaviors between zigzag tubes and armchair tubes. At some special torsion angles, the conductivity of zigzag tube and armchair tube has obvious changes, which reveals the translation between metal-type and semiconductor-type conductivities.
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