The dimeric indium thiolates [R2In(μ-StBu)]2 R = tBu (1), nBu (2), Me (3), and [(tBuS)MeIn(μ-St Bu)]2 (4) were synthesized and successfully applied as single source In-S precursors for the growth of In/InS and InS layers by MOCVD. metal-organic chemical vapor deposition (MOCVD). The dependence of the film composition (In-rich vs. stoichiometric InS) and structure (orthorhombic vs. tetragonal InS) on the deposition temperature and molecular precursor nature (1–3)/ possible decomposition pathways of the molecules was discussed with respect to the available to the precursor molecules.
The
synthesized indium thiolates were characterized by 1H and 13C NMR and mass spectrometry. The deposited InSx layers were characterized by the EDX, XPS and TEM. [[i] ]
[i] A.N. MacInnes, M.B. Power, A.F. Hepp, A.R. Barron, J. Organomet. Chem., 1993, Vol 449, Iss.1–2, p.95-104, https://www.sciencedirect.com/science/article/pii/0022328X9380111N, « Indium tert-butylthiolates as single source precursors for indium sulfide thin films: Is molecular design enough? »
Di(tert-butyl)indium (tert-butylthiolate) [tBu2In(μ-StBu)]2 (1) and di(n-butyl)indium (tert-butylthiolate) [nBu2In(μ-StBu)]2 (2) at atmospheric pressure produced indium rich films (InSx) consisting of In metal and orthorhombic InS at temperatures 290-350°C, whereas at 400°C a single phase tetragonal high pressure phase of InS was obtained.
Use of Dimetylindium (tert-butylthiolate) [Me2In(μ-StBu)]2 (3) as precursor resulted in amorphous In-rich films at 300°C growth temperature, whereas layers prepared at 400°C had ratio In: S ~1, consisting of an In-rich phase and In2S3.
Methylindium bis(tert-butylthiolate) [(tBuS)MeIn(μ-StBu)]2 (4) was proposed as a potential precursor for the growth of low temperature deposition of stoichiometric InS (its solid state pyrolysis yielded InS). Amorphous films of stoichiometric InS were obtained by low pressure MOCVD, Hhowever, upon annealing β-In2S3 crystalline phase was formed.