Electronic transport across extended grain boundaries in graphene
Electronic transport across extended grain boundaries in graphene
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DOI：
10.1088/2632-959x/ac0597
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发表时间：
2021-09-01
期刊：
影响因子：
3
通讯作者：
Aksamija, Zlatan
中科院分区：
文献类型：
--
作者：
Majee, Arnab K.;Aksamija, Zlatan
由于其最高的载流子迁移率和原子薄，石墨烯在未来的纳米电子集成电路中显示出巨大的潜力。化学气相沉积（CVD）是用于石墨烯的晶片级生长的最流行的方法，其产生多晶的单层，其中取向错误的晶粒被延伸的晶界（GB）分开。GB电阻率的理论模型集中在一个扩展GB的小部分，假设它是一条直线，并预测电阻率对取向差角的强烈依赖性。相比之下，测量产生的值范围要窄得多，没有明显的角度依赖性。在这里，我们研究电子输运粗糙GB，这是由短直段连接在一起，成为一个扩展GB。我们发现，由于粗糙的GB的锯齿形的性质，总是存在一些段，两个晶粒之间的结晶角对称地划分，并提供一个高导电性的路径，电流流过GB。高导电段的存在产生的电阻率在10（2）至10（4）Ω μ m之间，无论取向差角如何。具有大粗糙度和小相关长度的扩展GB具有10（3）Ω μ m量级的小电阻率，即使对于高度失配的非对称GB也是如此。由粗糙度与横向相关长度之比给出的GB有效斜率是GB电阻率的一个有效的通用量化器。我们的研究结果表明，发现导电段的概率在短GB中减小，这可能导致从多晶石墨烯蚀刻的窄带的电阻率的大的变化。我们还揭示了由于电流弯曲的晶粒中流过GB的导电段的扩展电阻，并表明它与晶粒电阻成线性比例。我们的研究结果将是至关重要的设计石墨烯为基础的互连未来的集成电路。
Owing to its superlative carrier mobility and atomic thinness, graphene exhibits great promise for interconnects in future nanoelectronic integrated circuits. Chemical vapor deposition (CVD), the most popular method for wafer-scale growth of graphene, produces monolayers that are polycrystalline, where misoriented grains are separated by extended grain boundaries (GBs). Theoretical models of GB resistivity focused on small sections of an extended GB, assuming it to be a straight line, and predicted a strong dependence of resistivity on misorientation angle. In contrast, measurements produced values in a much narrower range and without a pronounced angle dependence. Here we study electron transport across rough GBs, which are composed of short straight segments connected together into an extended GB. We found that, due to the zig-zag nature of rough GBs, there always exist a few segments that divide the crystallographic angle between two grains symmetrically and provide a highly conductive path for the current to flow across the GBs. The presence of highly conductive segments produces resistivity between 10(2) to 10(4) omega mu m regardless of misorientation angle. An extended GB with large roughness and small correlation length has small resistivity on the order of 10(3) omega mu m, even for highly mismatched asymmetric GBs. The effective slope of the GB, given by the ratio of roughness and lateral correlation length, is an effective universal quantifier for GB resistivity. Our results demonstrate that the probability of finding conductive segments diminishes in short GBs, which could cause a large variation in the resistivity of narrow ribbons etched from polycrystalline graphene. We also uncover spreading resistance due to the current bending in the grains to flow through the conductive segments of the GB and show that it scales linearly with the grain resistance. Our results will be crucial for designing graphene-based interconnects for future integrated circuits.