Abstract: Si-containing film forming compositions comprising Si—C free and volatile silazane-containing precursors are disclosed. The compositions may be used to deposit high purity thin films. The Si—C free and volatile silazane-containing precursors have the formulae: [(SiR3)2NSiH2]m—NH2-m—C?N, with m=1 or 2;??(a) [(SiR3)2NSiH2]n—NL3-n,with n=2 or 3;??(b) (SiH3)2NSiH2—O—SiH2N(SiH3)2; and??(c) (SiR?3)2N—SiH2—N(SiR?3)2;??(d) with each R independently selected from H, a dialkylamino group, or an amidinate; each R? independently selected from H, a dialkylamino group, or an amidinate, with the provision that all R? are not H; and L is selected from H or a C1-C6 hydrocarbyl group.