Gamal Sarah, Fadlallah Mohamed M, Salah Lobna M, Maarouf Ahmed A
Department of Physics, Faculty of Science, Cairo University, Giza 12613, Egypt.
Nanotechnology. 2020 Nov 27;31(48):485710. doi: 10.1088/1361-6528/abb04d.
Graphene nanomeshes (GNMs) are novel materials that recently raised a lot of interest. They are fabricated by forming a lattice of pores in graphene. Depending on the pore size and pore lattice constant, GNMs can be either semimetallic or semiconducting with a gap large enough (∼ 0.5 eV) to be considered for transistor applications. The fabrication process is bound to produce some structural disorder due to variations in pore size. Recent electronic transport measurements in GNM devices (ACS Appl. Mater. Interfaces 10, 10 362, 2018) show a degradation of their bandgap in devices having pore-size disorder. It is therefore important to understand the effect of such variability on the electronic properties of semiconducting GNMs. In this work we use the density functional-based tight binding formalism to calculate the electronic properties of GNM structures with different pore sizes, pore densities, and with hydrogen and oxygen pore edge passivations. We find that structural disorder reduces the electronic gap and the carrier group velocity, which may interpret recent transport measurements in GNM devices. Furthermore, the trend of the bandgap with structural disorder is not significantly affected by the change in pore edge passivation. Our results show that even with structural disorder, GNMs are still attractive from a transistor device perspective.
石墨烯纳米网（GNMs）是最近引起广泛关注的新型材料。它们是通过在石墨烯中形成孔晶格来制造的。根据孔径和孔晶格常数，GNMs可以是半金属的，也可以是具有足够大间隙（约0.5电子伏特）的半导体，可用于晶体管应用。由于孔径的变化，制造过程必然会产生一些结构无序。最近在GNM器件中的电子输运测量（《美国化学会应用材料与界面》10, 10362, 2018）表明，在具有孔径无序的器件中，其带隙会退化。因此，了解这种变异性对半导体GNMs电子特性的影响很重要。在这项工作中，我们使用基于密度泛函的紧束缚形式来计算具有不同孔径、孔密度以及氢和氧孔边缘钝化的GNM结构的电子特性。我们发现结构无序会降低电子能隙和载流子群速度，这可以解释最近在GNM器件中的输运测量结果。此外，带隙随结构无序的变化趋势不受孔边缘钝化变化的显著影响。我们的结果表明，即使存在结构无序，从晶体管器件的角度来看，GNMs仍然具有吸引力。
