ABSTRACT Atomic/molecular layer deposition (ALD/MLD) offers a comprehensive process and application portfolio for metal–organic thin films; however, ALD/MLD process development for transition‐metal‐based materials remains very limited, despite the versatile functional properties of their compounds. In this work, to enrich the chemistry of transition metal precursors in ALD/MLD, an all‐nitrogen‐coordinated cobalt complex, Co(tmsaedma) 2 (tmsaedma = Bis(N,N‐dimethyl(N’‐trimethylsilyl)ethane‐1‐amino‐2‐amido), was employed as the metal precursor for the first time. The Co‐N coordination provides an optimal reactive site for a variety of organic linker groups, as demonstrated here by three organic precursors that share the same rigid benzene backbone but differ in reactive groups: 1,4‐benzenediol (hydroquinone; HQ), 1,4‐benzenedithiol (BDT), and 1,4‐benzenedicarboxylic acid (terephthalic acid; BDC). A comprehensive set of characterization techniques, combined with first principles density functional theory (DFT) calculations, is used to systematically investigate the three new ALD/MLD processes and the stability of the resulting Co(II)‐organic thin films: Co‐HQ, Co‐BDT, and Co‐BDC. The reactivity and stability trends of the organics are found as BDC>HQ>BDT and BDC>>BDT>>HQ, respectively. Decomposition mechanisms are provided for Co‐HQ and Co‐BDT. Furthermore, the preparation of low‐density, porous CoO thin films with tunable structural and optical properties, difficult to achieve otherwise, is demonstrated via calcination in N 2 of the Co‐BDC thin films.
Jussila et al. (Sat,) studied this question.