Few-layer MoS2 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 electrical property. Control of the rf power could change the work function of MoS2 from 5.40 eV to 5.06 eV. It is shown that the increased rf power leads to the increased (reduced) number of nitrogen (oxygen) atoms, increasing the electron concentration and shifting the Fermi level toward conduction band. The sensitivity of the work function to the rf power provides an opportunity to tune the work function of MoS2.

Charge trapping properties of electrons and holes in copper-doped zinc oxide (ZnO:Cu) films have been studied by scanning probe microscopy. We investigated the surface potential dependence on the voltage and duration applied to the copper-doped ZnO films by Kelvin probe force microscopy. It is found that the Fermi Level of the 8 at.% Cu-doped ZnO films shifted by 0.53 eV comparing to undoped ZnO films. This shift indicates significant change in the electronic structure and energy balance in Cu-doped ZnO films. The Fermi Level (work function) of zinc oxide films can be tuned by Cu doping, which are important for developing this functional material. In addition, Kelvin probe force microscopy measurements demonstrate that the nature of contact at Pt-coated tip/ZnO:Cu interface is changed from Schottky contact to Ohmic contact by increasing sufficient amount of Cu ions. The charge trapping property of the ZnO films enhance greatly by Cu doping (~10 at.%). The improved stable bipolar charge trapping properties indicate that copper-doped ZnO films are promising for nonvolatile memory applications.

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The fabrication of memory devices based on the Au/NiO/heavily doped p-type Si (p+-Si) structures and their current-voltage characteristics were reported. The Au/NiO/p+-Si devices show hysteresis behavior. The fitting data of the temperature-dependent off-state current–voltage curves demonstrated that the carrier transport mechanism of the Au/NiO/p+-Si device was attributed to the space change limited conduction. However, the difference between the temperature-dependent on-state currents in the forward-bias and reverse-bias regions was found. The different electrical conduction mechanisms (hopping conduction and Ohmic conduction with metal-like behaviors) were discussed. This phenomenon is related to the different interfacial characteristics between Au/NiO and NiO/p+-Si.

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