Deposition and Microstructures of Non-Conductive Indium Coatings on PMMA Plate:An Atomic Force Microscopy Study

The non-conductive indium coatings were deposited by e-beam evaporation on polymethylmethacrylate (PMMA) plate.The impact of the thickness on the microstructures and electrical properties of the indium thin films was investigated with atom force microscopy.The preliminary results show that the coverage or thickness strongly affected the surface morphology and electrical properties of the In-coating.To be specific, in the initial growth stage, the 3-D isolated indium islands formed on the substrate and the films were non-conductive.As the thickness increased, the isolated islands grew into a continuous film and the surface roughness decreased.Growing thicker than 120 nm, the sheet resistance and surface roughness markedly decreased and randomly distributed pores covered the surfaces of compact films.The smooth compact indium coating,~160 nm in thickness, was found to be conductive with a sheet resistance of~3 Ω/□.