Disclosed are silicon and carbon containing film forming compositions comprising a polycarbosilazane polymer or oligomer formulation that consists of silazane-bridged carbosilane monomers, the carbosilane containing at least two —SiH2— moieties, either as terminal groups (—SiH3R) or embedded in a carbosilane cyclic compound, wherein R is H, a C1-C6 linear, branched, or cyclic alkyl- group, a C1-C6 linear, branched, or cyclic alkenyl- group, or combination thereof. Also disclosed are methods of forming a silicon and carbon containing film comprising forming a solution comprising a polycarbosilazane polymer or oligomer formulation and contacting the solution with the substrate via a spin-on coating, spray coating, dip coating, or slit coating technique to form the silicon and carbon containing film.