First-principles electronic transport calculations of graphene nanoribbons on SiO₂/Si

Abstract

We study the electronic transport properties of graphene nanoribbons (GNRs) on SiO2/Si with O-terminated (siloxane) or OH-terminated (silanol) surfaces. The channel length and SiO2 thickness are 9.91 and 0.45 nm, respectively. The GNR shows p-type conduction on both the SiO2/Si surfaces. More holes are injected from OH groups in the silanol SiO2 to GNRs. The on/off current ratio for both GNRs on SiO2/Si is 103–105, which is consistent with recent experiments, and smaller by a factor of 108 than those of freestanding GNRs. The ratio is even smaller on the p side for the silanol SiO2.

Electronic transport properties of graphene channel with metal electrodes or insulating substrates in 10 nm-scale devices

“…The model with L ¼ 9.91 nm in Ref. 26 was almost the same as this model. Note that the transport direction is perpendicular to the ribbon width, contrary to the graphene/metal electrodes model in Sec.…”

“…[21][22][23][24][25] Regarding the electronic transport properties, we previously reported on the first-principles study of AGNRs with the channel length L ¼ 9.91 nm on O-and OH-terminated SiO 2 /Si surfaces. 26 The on/off current ratio for AGNRs on both the surfaces is less than that of the freestanding (FS) AGNR. However, more comprehensive research is necessary to understand the dependence of channel length on the transport properties.…”

“…On the other hand, the electronic properties of graphene are significantly fragile against the surrounding foreign materials, such as metal electrodes [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and insulating substrates. [15][16][17][18][19][20][21][22][23][24][25][26] This is because the whole area of graphene intrinsically forms interfaces with such foreign materials. The fragility of the electronic properties will constitute a serious problem for designing the graphene-based electronic devices especially in the 10 nm-scale, which is considered for future realization when graphene devices can potentially be used in practice.…”

Electronic Transport Properties of Graphene Channel between Au Electrodes

“…Theoretical calculations have also demonstrated that graphene possesses finite energy gap with a few tens meV by adsorbing on surfaces of α-quartz [5][6][7]. Moreover, our first-principles electronic transport study of graphene nanoribbons (GNRs) on SiO 2 /Si uncovered the variation of the transmission probability depending on the surface morphologies [8].…”

“…A honeycomb network with atom thickness leads to a massless electron/hole around the Fermi level that allows the material to be applied to highspeed electronic devices in the post-silicon era. On the other hand, electronic properties of graphene are fragile when hybrid structures are formed with other foreign materials, such as insulating substrates [1][2][3][4][5][6][7][8] and metal electrodes [9][10][11][12][13][14][15][16][17][18], because the electron system of graphene is distributed normal to their atomic network that intrinsically forms interfaces with such foreign materials. This fragility of the electronic structure is a serious problem for realizing graphene-based electronic devices.…”