Micro-morphological investigations on wettability of Al-incorporated c-Si thin films using statistical surface roughness parameters

The tunable surface properties of Al-incorporated c-Si and/or homogeneous c-Si (i.e., absorber layer) thin films are investigated with the help of 3D surface topography, statistical analysis, and contact angle measurement. The absorber layers are developed by ion irradiation on c-Al/a-Si films, which results the crystallization of Si in bilayer films, and the top unreacted Al layers were chemically etched off by wet selective etching. The 3D surface topography and statistical analysis is performed on the atomic force microscopy images of the absorber film surface. The analyses suggest that the surfaces are highly complex and irregular isotropic. The surface roughness and irregularity is found to be decreasing with increasing ion fluence. Variation of contact angle with statistical parameters suggest that the wettability of the absorber surface strongly depends on the surface statistical parameters. The surfaces are hydrophobic in nature, and hydrophobicity is found to decrease with increasing ion fluence. The hydrophobic nature of low reflective absorber surface suggests that the film may be useful as a photon absorber layer for advance solar cell applications.