The study revealed that the nature of the AlN (0001) surface could play a fundamental role in the growth mode of metals. In the case of silver (Ag) deposited on the AlN(0001) (2×2)‐Nad reconstructed surface, the growth mode was Volmer–Weber. Deposition of indium (In) on a contaminated AlN(0001) surface leads to the formation of a wetting layer, followed by a 3D growth mode. For magnesium (Mg), a wetting layer was observed on the clean and contaminated surface followed by a 2D growth mode. Finally, the Au case was the most interesting since on the contaminated surface and the (2×2)‐Nad reconstructed surface, the growth mode was 3D and 2D, respectively, without the formation of a wetting layer. The Kelvin probe force microscopy (KPFM) study allowed to get qualitative and quantitative information about the work function of cluster and islands observed for the different metals on the AlN(0001) surface.
Charging of 2D Au nanoplatelets deposited on an insulating SiO2 substrate to or from the tip of a non-contact atomic force microscope (nc-AFM) is demonstrated. Charge transfer is controlled by monitoring the resonance frequency shift Δf(V) during the bias voltage ramp V applied to the tip-back electrode junction. The onset of charge transfer is revealed by a transition from a capacitive parabolic behavior to a constant Δf(V) region for both polarities. An analytical model, based on charging by electron field emission, shows that the field-emitted current saturates shortly after the onset of the charging, due to the limiting effect of the charge-induced rise of the Au platelet potential. The value of this current plateau depends only on the rate of the bias voltage ramp and on the value of the platelet/SiO2/back electrode capacitance. This analysis is confirmed by numerical simulations based on a virtual nc-AFM model that faithfully matches the experimental data. Our charging protocol could be used to tune the potential of the platelets at the single charge level.
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