Abstract

The effect of vacancy defects on electrons transport behavior of the alpha-armchair graphyne nanoribbons has been studied by density-functional tight-binding and non-equilibrium Green’s function methods. Three different widths of the nanoribbons with 6, 7 and 8 atoms and four types of vacancy defects contain one, two, three and four missing atoms were selected in this study. In relaxed structures, the structural changes around the defects are observed. Some of the free hands form new atomic chains containing 6 or 7 atoms. Comparing with perfect devices, the current decreases at the defective devices with 8 atoms width, whereas, it increases for devices with 6 atoms width. By calculating the density of states, transmission spectrums and molecular energy spectrums for devices with 6-atoms widths, there is a resonance state for DDOS and T(E) peaks in the QV device, while the peak of the density of states and transmission spectrums does not match in the SV1 device. Also, the results show that HOMO-LUMO gap energy in the SV1 device is much more than the perfect and QV devices. For devices with 8 atoms width, the transmission spectrums are reduced for all defects due to the lower density of the energy level of molecular energy. However, the orbital distribution of LUMO state in the device with the defect is localized but for the perfect structure, both the LUMO and the HOMO orbital distribution are quite delocalized.

Graphical abstract

中文翻译：

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空位缺陷对α-扶手椅石墨烯纳米带传输性能的影响

摘要

通过密度-功能紧密结合和非平衡格林函数方法研究了空位缺陷对α-扶手椅石墨烯纳米带的电子传输行为的影响。在这项研究中，选择了具有6个，7个和8个原子的三种不同宽度的纳米带以及四种类型的空缺缺陷，这些空缺包含一个，两个，三个和四个缺失原子。在松弛的结构中，观察到缺陷周围的结构变化。一些自由手形成包含6或7个原子的新原子链。与完善的器件相比，有缺陷的器件在原子宽度为8的情况下电流会减小，而在有原子的宽度为6的器件处电流会增加。通过计算具有6个原子宽度的器件的状态密度，透射光谱和分子能谱，QV设备中的DDOS和T（E）峰存在谐振状态，而SV1设备中的状态密度和传输频谱的峰不匹配。同样，结果表明，SV1器件中的HOMO-LUMO间隙能远远超过完美和QV器件。对于原子宽度为8的器件，由于分子能级的能量密度较低，所有缺陷的透射光谱都会降低。然而，具有缺陷的装置中LUMO状态的轨道分布是局部的，但是对于完美的结构，LUMO和HOMO的轨道分布都相当离域。对于原子宽度为8的器件，由于分子能级的能量密度较低，所有缺陷的透射光谱都会降低。然而，具有缺陷的装置中LUMO状态的轨道分布是局部的，但是对于完美的结构，LUMO和HOMO的轨道分布都相当离域。对于原子宽度为8的器件，由于分子能级的能量密度较低，所有缺陷的透射光谱都会降低。然而，具有缺陷的装置中LUMO状态的轨道分布是局部的，但是对于完美的结构，LUMO和HOMO的轨道分布都相当离域。

图形概要