Fig. 2: The spectral function of the carbon nanotube at varying carbon nanotube/graphene spacing.
From: Contact spacing controls the on-current for all-carbon field effect transistors
The interaction strength between the graphene electrode and the carbon nanotube (CNT) on top is related to the broadening of the peaks in the spectral function A(E, kz): strong interactions cause smearing of A(E, kz). The spectral function is plotted in a 2D-heatmap plot over the Energy E (with respect to the Fermi level EF) and the wavevector kz. a At a spacing of dgr/CNT = 5.0 Å, the peaks are sharp and distinct. Smaller spacings lead to a smearing of the peaks, although the key features (bands and bandgap) are still visible (b and c). d At a spacing of 3.0 Å, some bands overlap while the semiconducting property of the CNT remains. This indicates that graphene electrodes do not destroy the semiconducting property of the CNT by metalizing it, as reported for Ni or Ti contacts27. The scale bar shows the logarithmic spectral function \({{{{{{\mathrm{log}}}}}}}\,A(E,{k}_{{{\mbox{z}}}})\) normalized to the range of values between 0 and 1.
