Structural and electrical properties of porous silicon with rf-sputtered Cu films

Thin semi-transparent Cu films were deposited at room temperature, using rf-sputtering on porous silicon (PS). The porous layer with the thickness of about 15–17 μm were obtained on p-type (100) silicon wafers, by applying various current densities viz. 25, 45, 65 and 85 mA cm−2. Various thicknesses of Cu films ranging from 45 to 170 Å were obtained by varying sputtering time. The red shift from 620 to 750 nm was observed in PL peaks for the Cu deposited PS. To analyze the surface morphology of the films scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses of the films were carried out. The surface roughness of Cu films as measured from AFM varies from 0.669 to 1.8575 nm. The refractive index (RI) of the films measured by ellipsometry, varies from 1.38 to 1.95 with increasing Cu film thickness. The I–V characteristics show the shift of the barrier from 0.65 to 0.77 eV with decreasing the etching current density from 85 to 25 mA cm−2.