Tantalum compounds of Formula I hereof are disclosed, having utility as precursors for forming tantalum-containing films such as barrier layers. The tantalum compounds of Formula I may be deposited by CVD or ALD for forming semiconductor device structures including a dielectric layer, a barrier layer on the dielectric layer, and a copper metallization on the barrier layer, wherein the barrier layer includes a Ta-containing layer and sufficient carbon so that the Ta-containing layer is amorphous. According to one embodiment, the semiconductor device structure is fabricated by depositing the Ta-containing barrier layer, via CVD or ALD, from a precursor including the tantalum compound of Formula I hereof at a temperature below about 400.degree. C. in a reducing or inert atmosphere, e.g., a gas or plasma optionally containing a reducing agent.