Graphene prepared by the chemical vapor deposition method was treated with nitrogen plasma under different radio-frequency (rf) power conditions in order to experimentally study the change in the work function. Control of the rf power could change the work function of graphene from 4.91 eV to 4.37 eV. It is shown that the increased rf power may lead to the increased number of graphitic nitrogen, increasing the electron concentration, and shifting the Fermi level to higher energy. The ability to controllably tune the work function of graphene is essential for optimizing the efficiency of optoelectronic and electronic devices.

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The current–voltage characteristics of graphene/Si-nanowire (SiNW) arrays/n-type Si Schottky diodes with and without H2O2 treatment were measured in the temperature range of −150 ∼ 150 °C. The forward-bias current-voltage characteristics were analyzed on the basis of thermionic emission theory. It is found that the barrier height decreases and the ideality factor increases with the decreased temperatures. Such behavior is attributed to barrier inhomogeneities. It is shown that both Schottky barrier inhomogeneity and the T0 effect are affected by H2O2 treatment, implying that charge traps in the SiNWs have a noticeable effect on Schottky barrier inhomogeneity for graphene/SiNWs/n-type Si diodes.

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