Template-Free Vapor-Phase Growth of Patrónite by Atomic Layer Deposition

Despite challenges to control stoichiometry in the vanadium–sulfur system, template-free growth of patrónite, VS 4, thin films is demonstrated for the first time. A novel atomic layer deposition (ALD) process enables the growth of phase pure films and the study of electrical and vibrational properties of the quasi-one-dimensional (1D) transition metal sulfide. Self-limiting surface chemistry during ALD of VS 4 is established via in situ quartz crystal microbalance and quadrupole mass spectrometry between 150 and 200 °C. The V precursor, unconventionally, sheds all organic components in the first half-cycle, while the H 2 S half-cycle generates the disulfide dimer moiety, S 2 –2, and oxidizes V 3+ to V 4+ . X-ray analysis establishes VS 4 crystallinity and phase purity, as well as a self-limiting growth rate of 0.33 Å/cy, modest roughness of 2.4 nm, and expected density of 2.7 g/cm 3 . Phase pure films enable a new assignment of vibrational modes and corresponding Raman activity of VS 4 that is corroborated by density functional theory (DFT) calculations. Finally, at elevated growth temperatures, a change in the surface mechanism provides a synthetic route to a second vanadium–sulfur phase, V 2 S 3 .