Atomic layer deposition (ALD) processes for forming Te-containing thin films, such as Sb—Te, Ge—Te, Ge—Sb—Te, Bi—Te, and Zn—Te thin films are provided. ALD processes are also provided for forming Se-containing thin films, such as Sb—Se, Ge—Se, Ge—Sb—Se, Bi—Se, and Zn—Se thin films are also provided. Te and Se precursors of the formula (Te,Se)(SiR1R2R3)2 are preferably used, wherein R1, R2, and R3 are alkyl groups. Methods are also provided for synthesizing these Te and Se precursors. Methods are also provided for using the Te and Se thin films in phase change memory devices.