Methods of fabricating a semiconductor structure with a non-epitaxial thin film disposed on a surface of a substrate of the semiconductor structure; and semiconductor structures formed thereof are disclosed. The methods provide selective non-epitaxial growth (SNEG) or deposition of amorphous and/or polycrystalline materials to form a thin film on the surface thereof. The surface may be a non-crystalline dielectric material or a crystalline material. The SNEG on non-crystalline dielectric further provides selective growth of amorphous/polycrystalline materials on nitride over oxide through careful selection of precursors-carrier-etchant ratio. The non-epitaxial thin film forms resultant and/or intermediate semiconductor structures that may be incorporated into any front-end-of-the-line (FEOL) fabrication process. Such resultant/intermediate structures may be used, for example, but are not limited to: source-drain fabrication; hardmask strengthening; spacer widening; high-aspect-ratio (HAR) vias filling; micro-electro-mechanical-systems (MEMS) fabrication; FEOL resistor fabrication; lining of shallow trench isolations (STI) and deep trenches; critical dimension (CD) tailoring and claddings.