GADOLINIUM ALKYLGUANIDINATES

Gadolinium tris(N,N’-isopropyl-N’’-dimethylguanidinate) [Gd{(iPrN)2CNMe2}3]

Gadolinium tris(N,N’-isopropyl-N’’-diethylguanidinate) [Gd{(iPrN)2CNEt2}3]

Gadolinium tris(N,N’-isopropyl-N’’-diisopropylguanidinate) [Gd{(iPrN)2CNiPr2}3]

Fig. TGA curve of Gd[(NiPr)2CNMe2]3

       Homoleptic Gd tris-guanidinates complexes Gd[(NiPr)2CNR2]3 R = Me (1), Et (2), iPr (3)] (and for comparison analogous Y, Dy compounds) have been synthesized and characterized by microanalysis (C,H,N), IR spectroscopy, NMR, mass spectrometry. All complexes are monomers with 6-fold coordination of Gd atom by N atoms of the three chelating guanidinato ligands in a distorted trigonal prism geometry, according to single crystal XRD analysis.

       Thermal characteristics of all 3 complexes were investigated by TGA/DTA and isothermal TGA to evaluate their suitability as MOCVD/ ALD precursors.  Excellent thermal characteristics (thermal stability and volatility) were observed for the gadolinium iPr-Me2N-guanidinate. Thus, gadolinium iPr-Me2N-guanidinates demonstrated the prerequisites for their application as precursors for MOCVD and ALD applications -  confirmed by the successful deposition of Gd2O3 layers on Si(100) substrates (with ALD films were amorphous, whereas MOCVD -grown Gd2O3films were highly oriented in the cubic phase, while the ALD grown films were amorphous.[i]

[i] A.P. Milanov, R.A. Fischer, A. Devi, Inorg. Chem., 2008, 47 (23), pp 11405–11416, DOI: 10.1021/ic801432b, “Synthesis, Characterization, and Thermal Properties of Homoleptic Rare-Earth Guanidinates: Promising Precursors for MOCVD and ALD of Rare-Earth Oxide Thin Films”

[Gd{(iPrN)2CNMe2}3] for GdN films by MOCVD

      Gadolinium tris(N,N’-isopropyl-N’’-dimethylguanidinate) [Gd{(iPrN)2CNMe2}3] was successfully applied as single source precursor for the growth of GdN thin films [[i]]

[i] A.P. Milanov, T.B. Thiede, A. Devi, R.A. Fischer, J. Am. Chem. Soc., 2009, 131 (47), pp 17062–17063, DOI: 10.1021/ja907952g Homoleptic Gadolinium Guanidinate: A Single Source Precursor for Metal−Organic Chemical Vapor Deposition of Gadolinium Nitride Thin Films

[Gd{(iPrN)2CNMe2}3] for Gd2O3 films by MOCVD

    Tris(N,N’-diisopropyl-2-dimethylamido-guanidinato)gadolinium (III) Gd{(iPrN)2CNMe2}3] has been applied as precursor the deposition of Gd2O3 films by MOCVD. NMR decomposition studies revealed the extraordinary thermal stability of the precursor. The precursor is very volatile, according to the detailed TGA and isothermal TGA studies, and thus able to deliver continuous mass transport into the gas phase.

      Gd2O3 growth on Si(100) and Al2O3(0001) substrates using Gd{(iPrN)2CNMe2}3] precursor was carried out at 300−700 °C substrate temperatures at reduced pressure in the presence of O2. Uniform reproducible quality Gd2O3 films were obtained over the entire temperature range; the variations of growth characteristics and layer properties  (crystallinity, structure, surface roughness, composition, and electrical properties) with deposition temperature were investigated by XRD, SEM, AFM, EDX, XPS, RBS, SNMS and C−V.[i],[ii]

[i] A.P. Milanov, T. Toader, H. Parala, D. Barreca, A. Gasparotto, C. Bock, H.-W. Becker, D.K. Ngwashi, R. Cross, Sh. Paul, U. Kunze, R.A. Fischer, A. Devi, Chem. Mater., 2009, 21 (22), pp 5443–5455, DOI: 10.1021/cm902123m , “Lanthanide Oxide Thin Films by Metalorganic Chemical Vapor Deposition Employing Volatile Guanidinate Precursors”

[ii] A. P. Milanov, T. Thiede, M. Hellwig, H. Parala, C. Bock, H. W. Becker, D. K. Ngwashi, R. B. M. Cross, Sh. Paul, U. Ukunze, R.A. Fischer, A. Devi, ECS Trans., 2009, 25 (8), pp.143-150, DOI: http://dx.doi.org/10.1149/1.3207585, https://www.dora.dmu.ac.uk/handle/2086/3384, “Rare-Earth based Oxide and Nitride thin films employing volatile homoleptic guanidinate precursors.”

    The principal core levels of nanostructured Gd2O3 thin films grown by MOCVD from Gd((iPrN)2CNMe2)3 at 500 °C temperature in an N2/O2 atmosphere were studied by XPS. The XPS data of the grown Gd2O3 films revealed co-presence of gadolinium carbonates/bicarbonates and hydroxides in the film surface, evidencing significant Gd2O3 reactivity towards atmospheric CO2 and H2O.[i]

[i] D. Barreca, A. Gasparotto, A. Milanov, E. Tondello, A. Devi, R.A. Fischer, Surf. Sci. Spectra 14, 60 (2007); http://dx.doi.org/10.1116/11.20080703 (8 pages), “Gd2O3 Nanostructured Thin Films Analyzed by XPS”

[Gd{(iPrN)2CNMe2}3] (+H2O) for Gd2O3 films by ALD

Homoleptic gadolinium guanidinate precursor [Gd(DPDMG)3]  ([Gd{(iPrN)2CNMe2}3] ) was applied for the surface-controlled, self-limiting growth of Gd2O3 layers  on Si(100) substrates by a H2O-based ALD process. High-quality Gd2O3 layers were obtained at reasonable growth rates, the demonstrated promising electrical properties and a high-quality film/substrate interface without the need for any extra surface treatment prior to the layer growth.[[i]]

[i] A.P. Milanov, K. Xu, A. Laha, E. Bugiel, R. Ranjith, D. Schwendt, H. Jörg Osten, H. Parala, R.A. Fischer, A. Devi, J. Am. Chem. Soc., 2010, 132 (1), pp 36–37, DOI: 10.1021/ja909102j, „Growth of Crystalline Gd2O3 Thin Films with a High-Quality Interface on Si(100) by Low-Temperature H2O-Assisted Atomic Layer Deposition”

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