Molybdenum(iv) dithiocarboxylates as single-source precursors for AACVD of MoS2 thin films

Abstract

Tetrakis(dithiocarboxylato)molybdenum(IV) complexes of the type Mo(S₂CR)₄ (R = Me, Et, ⁱPr, Ph) were synthesized, characterized, and prescreened as precursors for aerosol assisted chemical vapor deposition (AACVD) of MoS₂ thin films. The thermal behavior of the complexes as determined by TGA and GC-MS was appropriate for AACVD, although the complexes were not sufficiently volatile for conventional CVD bubbler systems. Thin films of MoS₂ were grown by AACVD at 500 °C from solutions of Mo(S₂CMe)₄ in toluene. The films were characterized by GIXRD diffraction patterns which correspond to a 2H-MoS₂ structure in the deposited film. Mo–S bonding in 2H-MoS₂ was further confirmed by XPS and EDS. The film morphology, vertically oriented structure, and thickness (2.54 μm) were evaluated by FE-SEM. The Raman E¹_2g and A_1g vibrational modes of crystalline 2H-MoS₂ were observed. These results demonstrate the use of dithiocarboxylato ligands for the chemical vapor deposition of metal sulfides.