Electrical characterization of electrodeposited indium sulfide thin films by electrochemical impedance spectroscopy and electrical force microscopy

Abstract

In this work, we present the use of impedance spectroscopy and electrostatic force microscopy for the electrical characterization of ~100 nm indium sulfide thin films. We demonstrated the usefulness of impedance spectroscopy, as it was possible to characterize films with thicknesses so thin that they were impossible to detect by X-ray diffraction or ultraviolet spectroscopy. Impedance spectroscopy was used also to characterize grain boundaries, as well as for determining the n-type conductivity of the material. On the other hand, using spreading resistance microscopy, we mapped the surface, and we located the points with higher current flow. Using electrostatic force microscopy we measured the phase angle, which in turn was correlated with voltage drops at the interphase substrate/film in order to calculate the work function of indium sulfide, we have proposed also a scheme for conduction band locations at the interphase between the fluorine tin oxide substrate and the indium sulfide film.