Variability of bandgap and carrier mobility caused by edge defects in ultra-narrow graphene nanoribbons

Photoluminescent Semiconducting Graphene Nanoribbons via Longitudinally Unzipping Single-Walled Carbon Nanotubes

“…The field-effect carrier mobility is calculated using the following equation , where t oxide is the thickness of SiO 2 , ϵ is the relative dielectric constant of SiO 2 , L and W are the channel length and width, respectively. The mobility of the GNR-FET was calculated as 840 cm 2 /V s. This is also, to the best of our knowledge, the highest mobility reported in semiconducting GNRs so far and close to the theoretical scattering limit of ∼1000 cm 2 /V s in sub-3 nm wide GNRs at room temperature . This result indicates that the obtained GNRs are of high quality and close to pristine, which is in line with the spectroscopic analysis.…”

“…The mobility of the GNR-FET was calculated as 840 cm 2 /V s. This is also, to the best of our knowledge, the highest mobility reported in semiconducting GNRs so far and close to the theoretical scattering limit of ∼1000 cm 2 /V s in sub-3 nm wide GNRs at room temperature. 23 This result indicates that the obtained GNRs are of high quality and close to pristine, which is in line with the spectroscopic analysis.…”

“…Owing to its exceptional electronic, thermal, and mechanical properties, graphene has attracted huge interest in a broad research community and is considered as a potential replacement or complement for silicon in future electronics, as conventional electronics approaches the scaling limit. − However, the lack of an inherent band gap leads to a low current on/off ratio in graphene-based field-effect transistors (FETs), typically less than 10, which considerably prohibits their applications in electronics. − Graphene nanoribbons (GNRs) therefore attract increasing attention due to their semiconducting nature, − the band gap of which is generated by the lateral quantum confinement. Theoretical work predicts that GNRs are direct band gap semiconductors, thus also opening up numerous possibilities for realizing graphene-based optoelectronics. − To enable acceptable transistor performance, a minimum band gap of 0.7 eV, corresponding to a GNR width of less than 3 nm, is required. Such a width, however, has to date been extremely challenging to reliably achieve even by very advanced nanolithography techniques. , Therefore, several nonlithographic approaches have been explored to obtain GNRs, mainly by polycyclic molecular-based bottom-up synthesis and the unzipping of carbon nanotubes.…”

“…Theoretical work predicts that GNRs are direct band gap semiconductors, thus also opening up numerous possibilities for realizing graphene-based optoelectronics. 19−22 To enable acceptable transistor performance, a minimum band gap of 0.7 eV, corresponding to a GNR width of less than 3 nm, 23 is required. Such a width, however, has to date been extremely challenging to reliably achieve even by very advanced nanolithography techniques.…”

Effect of Edge Roughness on Static Characteristics of Graphene Nanoribbon Field Effect Transistor

“…Thus, modeling edge roughness is very useful to examine the effect of process variation on circuit performance of GNR FET. The dispersion of the electrical characteristics due to random edge defects in realistic nanoribbons can be precisely evaluated by statistical analysis at the device-level, based on the atomistic quantum transport simulations of large ensembles of randomly-generated GNRs [9]. Figure 1 shows the 3D view of a GNR FET, where the ribbon of the armchair chirality GNR is the channel material in a MOSFET-like structure.…”