碳纳米管从硅基板上剥离的拉伸分子动力学模拟研究

采用拉伸分子动力学方法研究了单壁碳纳米管(8, 8)在室温下从硅基板上被剥离的过程.当碳纳米管(CNT)在硅基底上被剥离时, 剥离距离和理想弹簧所测平均剥离力之间呈现一定规律的关系曲线,并出现了较大的正、负峰值. 比较了不同剥离速度下的平均剥离力,并拟合了其峰值与速度的关系. 拉伸分子动力学模拟结果显示,所需剥离力的最大值与速度之间呈现一定的线性关系, 模拟结果同生物物理学上类似的剥离实验结果符合较好,但相比于高分子, CNT和硅(Si)组成的界面吸附性能更强.讨论了碳纳米管长度、 半径及缺陷对剥离过程的影响,研究表明:所需最大的剥离力与CNT的长度无关, 但随CNT半径的增加,需要的最大剥离力线性增加; 5-7-7-5缺陷对剥离力最大值影响较小,而半径变化缺陷会削减最大剥离力. 在原子尺度对未来的试验进行了理论预测,为碳纳米管在硅微电子工业中的应用提供了理论基础.

Steered molecular dynamics simulation of peeling a carbon nanotube on silicon substrate

Steered molecular dynamics (SMD) simulations are performed to study the peeling of a single wall carbon nanotube (8, 8) from a silicon surface at room temperature. There is a regular relationship between the average force probed by the ideal spring and the peeling distance when the carbon nanotube (CNT) is peeled from the silicon substrate. A large positive and a large negative peak value can be found in the peeling process. The average force for varying peeling velocities is investigated and their peak values are fitted to a function of the peeling velocity. The SMD simulation results show that there is a linear relationship between the peak value and the peeling velocity, which is consistent well with some biophysics peeling experiments. Compared with macromolecules, the CNT has a strong adhesion to the silicon surface. The influences of both radius and length as well as the defects of the CNT on the peeling process are also examined. The numerical results indicate that the peak value of the peeling force is independent of the length of the CNT but increases linearly with the radius of the CNT increasing. The peak value of the peeling force is almost independent of the 5-7-7-5 defect in the CNT but critically weakened by the radius defect of the CNT. The suggested method provides a theoretical prediction for the future experiment at atomic scale, which is helpful for the potential application of the CNT in the silicon-based microelectronics industry.