I am Doing KPFM of TMDCs(MoS2, NbS2, WS2 and V2O3). I wonder i sometimes get very confusing values of contact potential difference. So, I want to ask weather I should ground both tip and my sample during every measurement regardless of their nature (semiconductor or metallic etc).
In order to get accurate contact potential difference measurements you must ground the sample. Otherwise, charging of the sample surface would distort the measured contact potential difference.
Dear Ali Sheraz.
The KPFM basically measures the electric force between tip and sample, it include workfunction, and eventual ions and charges on the sample surface. If you want really precise values for the workfunction, it need to be grounded and under UHV condition. Otherwise you will always have the influence of the environment.
Put the machine inside an environment with inert gas (N2) can also help the reproducibility of the measurement when you don't have UHV conditions. But the sample need to be always grounded to avoid charging of the sample surface, as pointed out by Alexei Ermakov.
Regards.
Thank you so much really, Alexei and Evandro Martin Lanzoni brothers.. Highly appreciated Evandro Martin Lanzoni
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