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选用C26N54原子簇模型来表征a—DLC网络的局域结构,研究表明,当在压应力作用下,a—DLC网络结构键长及键角会发生畸变,压应力的作用会使a—DLCsp2键构型向sp3键构型转换。这种构型的转换是个连续的过程,同时,应力弛豫也可使sp3键构型向sp2键构型转变,此时,相邻四面体间距将增大,当增至2.4A时,a—DLC网络可从稳定的晶体结构过渡至亚稳态的晶体结构。a—DLC网络电子态的研究表明,a—DLC网络价带高能位置主要由2p轨道电子占据,低能部分由2s轨道电子占据,2p电子的移动将影响此网络的禁带宽度。禁带宽度的变化与键角畸变关系不大,它主要由键长畸变引起,但键长的畸变往往伴随有键角的畸变。随着a—DLC网络相邻四面体间距的增大,该体系禁带宽度由晶态的54eV下降至2.13eV,此a—DLC网络禁带宽度计算结果与实验值一致。虽然结构畸变对禁带宽度影响很大,但对该体系总价带宽度影响不大。
The C26N54 atomic cluster model was used to characterize the local structure of the a-DLC network. The results show that when the compressive stress is applied, the bond length and bond angle of the a-DLC network will be distorted. The effect of compressive stress will make the a-DLCsp2 bond Conformation to sp3 bond configuration conversion. This configuration conversion is a continuous process, at the same time, the stress relaxation can also sp3 bond configuration transition to sp2 bond configuration, this time, the adjacent tetrahedron spacing will increase, when increased to 2.4A, The a-DLC network can transition from a stable crystalline structure to a metastable crystalline structure. A-DLC network electronic state studies show that, a-DLC network valence band position mainly occupied by the 2p orbital electrons, low-energy part of the 2s orbital occupied, 2p electron mobility will affect the bandgap of this network. The change of band gap has little relation with the key angle distortion, which is mainly caused by the key length distortion, but the key length distortion is often accompanied by the key angle distortion. As the distance between adjacent tetrahedra in a-DLC network increases, the forbidden band width of the system decreases from 54eV to 2.13eV. The calculation results of the forbidden band width of a-DLC network agree with the experimental ones. Although structural distortion has a great influence on the forbidden band width, it has little effect on the total band width of the system.