Copper(I) tert-Butylthiolato Clusters as Single-Source Precursors for High-Quality Chalcocite Thin Films: Film Growth and Microstructure Control

Soluble cluster compounds of polymeric (CuS t Bu) ∞ ( 1 ), such as the trialkylphosphine adducts [(CuS t Bu) 4 (PR 3 ) 2 ] (R = Me ( 2a ), Et ( 2b )) or the mixed ligand cluster Cu 7 (S t Bu) 4 (hfa) 3 (PMe 3 ) 3 ( 3, hfa = CH(COCF 3 ) 2 ), can be used as single-source precursors for chalcocite (α-Cu 2 S) film growth. Toluene or tetrahydrofuran solutions of 2a, 2b, or 3 afford high-quality chalcocite thin films on glass by aerosol-assisted chemical vapor deposition (AACVD). The films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, optical spectroscopy, and Hall effect electrical measurements. Surface morphologies were analyzed by scanning electron microscopy and atomic force microscopy. Phase-pure Cu 2 S films grown with 2a / b consist of large micrometer-scale plates, which lie flat on the substrate surface, resulting in an extraordinarily strong 〈00 l 〉 preferential orientation with respect to the hexagonal high -chalcocite substructure. The film morphologies as grown with precursor 3 suggest competing diketonate versus thiolate coordination at the {100} growth sites offering ligand-assisted film microstructural growth control.