Bishnoi Bhupesh, Buerkle Marius, Nakamura Hisao
National Institute of Advanced Industrial Science and Technology (AIST), Research Center for Computational Design of Advanced Functional Materials (CD-FMat), Central 2, Umezono 1-1-1, Tsukuba, Ibaraki, 305-8568, Japan.
Sci Rep. 2022 Jul 2;12(1):11214. doi: 10.1038/s41598-022-15098-6.
In this work, we benchmark non-idealities and variations in the two-dimensional graphene sheet. We have simulated more than two hundred graphene-based devices structure. We have simulated distorted graphene sheets and have included random, inhomogeneous, asymmetric out-of-plane surface corrugation and in-plane deformation corrugation in the sheet through autocorrelation function in the non-equilibrium Green's function (NEGF) framework to introduce random distortion in flat graphene. These corrugation effects inevitably appear in the graphene sheet due to background substrate roughness or the passivation encapsulation material morphology in the transfer step. We have examined the variation in density of state, propagating density of transmission modes, electronic band structure, electronic density, and hole density in those device structures. We have observed that the surface corrugation increases the electronic and hole density distribution variation across the device and creates electron-hole charge puddles in the sheet. This redistribution of microscopic charge in the sheet is due to the lattice fields' quantum fluctuation and symmetry breaking. Furthermore, to understand the impact of scattered charge distribution on the sheet, we simulated various impurity effects within the NEGF framework. The study's objective is to numerically simulate and benchmark numerous device design morphology with different background materials compositions to elucidate the electrical property of the sheet device.
在这项工作中，我们对二维石墨烯片的非理想性和变化进行了基准测试。我们模拟了两百多种基于石墨烯的器件结构。我们模拟了扭曲的石墨烯片，并通过非平衡格林函数（NEGF）框架中的自相关函数，在片中引入了随机、不均匀、不对称的面外表面波纹和面内变形波纹，以在平整的石墨烯中引入随机畸变。由于背景衬底粗糙度或转移步骤中钝化封装材料的形态，这些波纹效应不可避免地会出现在石墨烯片中。我们研究了这些器件结构中态密度、传播传输模式密度、电子能带结构、电子密度和空穴密度的变化。我们观察到，表面波纹增加了器件中电子和空穴密度分布的变化，并在片中产生了电子 - 空穴电荷 puddles。片中微观电荷的这种重新分布是由于晶格场的量子涨落和对称性破缺。此外，为了理解片上散射电荷分布的影响，我们在NEGF框架内模拟了各种杂质效应。该研究旨在通过数值模拟和基准测试具有不同背景材料成分的众多器件设计形态，以阐明片状器件的电学性质。
