For the first time, synthesis of two new amidinate-ligand comprising heteroleptic indium complexes, namely [InCl(amd)2] (1) and [InMe(amd)2] (2), via salt-metathesis and their detailed characterization is reported. For comparison, the earlier reported homoleptic tris-amidinate [In(amd)3] (3) was also synthesized and analyzed in detail especially with respect to the thermal properties and molecular crystal structure analysis which are reported here for the first time. From nuclear magnetic resonance spectroscopy (NMR) and single-crystal X-ray diffraction (XRD), all three compounds were found to be monomeric with C2 (compound 1 and 2) and C3 symmetry (compound 3). Both halide-free compounds 2 and 3 were evaluated regarding their thermal properties using temperature-dependent 1H-NMR, thermogravimetric analysis (TGA) and iso-TGA, revealing suitable volatility and thermal stability for their application as potential precursors for chemical vapor phase thin film deposition methods. Indeed, metalorganic chemical vapor deposition (MOCVD) experiments over a broad temperature range (400 °C-700 °C) revealed the suitability of these two compounds to fabricate In2O3 thin films in the presence of oxygen on Si, thermally grown SiO2 and fused silica substrates. The as-deposited thin films were characterized in terms of their crystallinity via X-ray diffraction (XRD), morphology by scanning electron microscopy (SEM) and composition through complementary techniques such as Rutherford-backscattering spectrometry (RBS) in combination with nuclear reaction analysis (NRA) and X-ray photoelectron spectroscopy (XPS). From UV/Vis spectroscopy, the deposited In2O3 thin films on fused silica substrates were found to be highly transparent (T > 95% at 560 nm, compound 3). In addition, Hall measurements revealed high charge carrier densities of 1.8 × 1020 cm-3 (2) and 6.5 × 1019 cm-3 (3) with a Hall-mobility of 48 cm2 V-1 s-1 (2) and 74 cm2 V-1 s-1 (3) for the respective thin films, rendering the obtained thin films applicable as a transparent conducting oxide that could be suitable for optoelectronic applications.

Two closely related mononuclear homoleptic indium-tris-guanidinate complexes have been synthesized and characterized as precursors for atomic layer deposition (ALD) of In2O3. In a water assisted ALD process, high quality In2O3 thin films have been fabricated for the first time using the new class of precursors as revealed by the promising ALD growth characteristics and film properties.

In2O3 thin films were grown by atomic vapor deposition (AVD) on Si(100) and glass substrates from a tris-guanidinate complex of indium [In(N(i)Pr2guanid)3] under an oxygen atmosphere. The effects of the growth temperature on the structure, morphology and composition of In2O3 films were investigated. X-ray diffraction (XRD) measurements revealed that In2O3 films deposited in the temperature range 450-700 degreesC crystallised in the cubic phase. The film morphology, studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM), was strongly dependent on the substrate temperature. Stoichiometric In2O3 films were formed under optimised processing conditions as was confirmed by X-ray photoelectron and X-ray excited Auger electron spectroscopies (XPS, XE-AES), as well as by Rutherford backscattering spectrometry (RBS). Finally, optical properties were investigated by photoluminescence (PL) measurements, spectroscopic ellipsometry (SE) and optical absorption. In2O3 films grown on glass exhibited excellent transparency (approximately 90%) in the Visible (Vis) spectral region.

Titanium oxide (TiO(2)) and titanium-tantalum oxide (Ti-Ta-O) thin films are deposited by liquid injection (LI) metal-organic (MO) CVD using metal amide-malonate complexes, [Ti(NR(2))(2)(dbmI)(2)], and tantalum, [Ta(NMe(2))(4)(dbml)] (R = Me, Et; dbml = di-tert-butylmalonato). TiO(2) and Ti-Ta-O films are deposited on Si (100) in the temperature ranges 350-650 degrees C and 500 - 700 degrees C, respectively. The structure, morphology, and chemical composition of the films are evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Rutherford backscattering spectroscopy (RBS), and X-ray photoelectron spectroscopy (XPS). The electrical properties of the films, namely the dielectric properties, are assessed by carrying out capacitance-voltage (C-V) measurements on metal-oxide-semiconductor (MOS) capacitor structures.

This work is focused on the evaluation of different Ga(III) precursor (conventional acetylacetonates, malonates and amides) for the MOCVD of Ga2O3 thin films. In particular, the attention is devoted to a thorough comparison of the precursor qualifying properties (volatility, thermal stability under the vaporization conditions) and their interrelations with the features of the obtained deposits. Samples were grown by thermal CVD and characterized by means of a multi-technique approach (X-ray diffraction {XRD}, scanning electron microscopy {SEM}, atomic force microscopy {AFM}, energy dispersive X-ray spectroscopy {EDXS}, X-ray photoelectron spectroscopy {XPS}, Rutherford backscattering spectrometry {RBS}, spectroscopic ellipsometry {SE}) to elucidate their microstructure, morphology and chemical composition, as well as their mutual interrelations with the synthesis conditions.

The application of the metalorganic compound tris(N,N'-diisopropyl-2-dimethlyamidoguanidinato)gadolinium(III) (1) as a precursor for MOCVD of Gd2O3 is discussed. Depositions were carried out in the presence of oxygen at reduced pressure and varying the substrate temperature in the range 300 - 700{degree sign}C. Employing a multi-technique approach (XRD, SEM, AFM, EDX, RBS, SNMS, SE, C-V), variations of the growth characteristics and film properties with deposition temperature are studied in terms of crystallinity, structure, surface roughness, composition, optical and electrical properties. In addition, the use of 1 as single source precursor for the MOCVD of GdN thin films is also demonstrated.

Five different homoleptic gallium complexes with malonic diester anions [Ga(ROCOCHOCOR)(3)] [R = Me (1), Et (2), iPr (3), tBu (4) and SiMe3 (5)] have been synthesised and characterised by H-1 and C-13 NMR, IR spectroscopy, electron ionisation mass spectrometry (EI-MS), and single-crystal X-ray diffraction. The thermal properties of the obtained compounds were evaluated by thermogravimetric studies to assess their suitability as precursors for the metal-organic chemical vapour deposition (MOCVD) of Ga2O3 thin films. MOCVD of Ga2O3 thin films was carried out starting from compound 2 in light of the promising features of this precursor. The as-deposited layers are amorphous and can be transformed into the monoclinic beta-Ga2O3 phase upon annealing at 1000 degrees C ex situ. The film morphology was studied by scanning electron microscopy (SEM), and its composition was investigated by energy-dispersive X-ray spectroscopy (EDXS) and X-ray photoelectron spectroscopy (XPS). Almost stoichiometric Ga2O3 thin films with low levels of carbon incorporation were obtained. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Mixed amido-malonato complexes of hafnium were synthesized by protolytic reactions of tetrakis-dialkylamido hafinium {[Hf(NR2)(4)], where R = Et-2 or EtMe} and di-tert-butylmalonate. The introduction of the bidentate malonate ligand stabilized the parent hafnium amide complexes by forming monomeric six coordinated compounds [Hf(NEt2)(2)(dbml)(2)] (1) and [Hf(NEtMe)(2)(dbml)(2)] (2). The novel complexes were fully characterised by means of single crystal X-Ray analysis, H-1- and C-13-NMR, EI-MS and CHN analysis. Furthermore both the complexes were found to possess suitable thermal properties for CVD application, They are soluble and stable in different organic solvents and hence investigated as precursors for liquid injection metalorganic chemical vapor deposition (LI-MOCVD) of HfO2 thin films. Compound I was tested in a multi-wafer planetary MOCVD, whereas compound 2 was tested in a smaller scale, state-of-the-art MOCVD reactor. HfO2 films deposition was achieved over wide temperature range and the films were crystallized in the monoclinic phase at >= 500 degrees C. The low temperature grown HfO2 films were smooth with a very low surface roughness (<0.4 nm). The electrical properties of metal insulator semiconductor (MIS) capacitor structures were also investigated and the relative dielectric permittivity reached the value of 22. In short, both the precursors are promising for the growth of high quality HfO2 films for high-k gate oxide application. (C) 2007 Elsevier B.V. All rights reserved.

A new zirconium complex, bis-(ethylmethylamido)-bis-(N,N'-diisopropyl-2-ethylmethylamidoguanidinato)-zirconium(iv) {[(N(i)Pr)(2)C(NEtMe)](2)Zr(NEtMe)(2)}, was synthesised by partial replacement of amide ligands with bidentate guanidinate ligands. The monomeric Zr complex was characterised by (1)H-NMR, (13)C-NMR, EI-MS, elemental analysis, and single crystal X-ray diffraction studies. The thermal properties of the compound was studied by thermogravimetric and differential thermal analysis (TG/DTA). The new Zr compound is thermally stable and can be sublimed quantitatively which renders it promising for thin film growth using vapor deposition techniques like chemical vapor deposition (CVD) and atomic layer deposition (ALD). The use of this complex for CVD of ZrO(2) on Si(100) substrates was attempted in combination with oxygen as the oxidant. Stoichiometric ZrO(2) films with preferred orientation at lower growth temperatures was obtained and the films were almost carbon free. The preliminary electrical characterisation of ZrO(2) films showed encouraging results for possible applications in dielectric oxide structures.

The stabilization of the reactive amide complexes of niobium and tantalum with malonates as chelating ligands leads to stable six-coordinated monomeric complexes ([M(NMe2)(4)(dbml)]; M = Nb, Ta), namely tetrakis(dimethylamido)(di-tert-butyli-nalonato)niobium(V) (1) and tetrakis(dimethylamido)(di-tert-butyl-malonato)tantalum(V) (2). Compounds 1 and 2 were characterized by H-1 NMR, C-13 NMR, EI-mass spectroscopy, elemental analysis, and single-crystal X-ray diffraction studies. The thermal properties of the Compounds were studied by thermogravimetric analysis. Both the complexes possess good thermal characteristies, improved resistance to air and moisture, and high solubility and stability in solvents compared to their respective parent alkyl amides. Compound I was studied for metalorganic chemical vapor deposition (MOCVD) of Nb2O5 while compound 2 was studied for liquid injection metalorganic chemical vapor deposition (LI-MOCVD) of Ta2O5 thin films. The films were deposited at substrate temperatures from 400 to 800 degrees C, and for both Nb2O5 and Ta2O5 the maximum growth rate was at 600 degrees C. The films were characterized by X-ray diffraction, scanning electron microscopy, and atomic force rnicroscopy for their crystallinity and morphology. Thin film composition was analyzed by X-ray photoelectron spectroscopy, Rutherford backscattering, and depth profiling the composition with secondary neutral mass spectrometry. Electrical properties of the films were studied in terms of the C-V characteristics.

Novel mixed amido-malonato complexes of titanium are reported. The complexes were synthesized by partially replacing the amido groups from the complexes [Ti(NMe2)4] and [Ti(NEt2)4] via Brønstedt acid/base reactions, using the malonate-ligands di-isopropylmalonate (Hdpml) and di-tert-butylmalonate (Hdbml). Four representative complexes were synthesized and fully characterised by 1H NMR, 13C NMR, CHN analysis and mass spectrometry. The crystal structures of the six-coordinated complexes [Ti(NMe2)2(dbml)2] (3) and [Ti(NEt2)2(dbml)2] (4) are presented and discussed. The complexes are solids and the chemical and thermal characteristics of the complexes strongly depend on the substitution at the malonate ligand. While dpml containing complexes show a promising behaviour for classical MOCVD, dbml containing complexes seem to be more suitable for liquid injection-metal-organic chemical vapour deposition (LI-MOCVD). Based on its thermal characteristics, the most promising complex for thermal CVD, [Ti(NEt2)2(dpml)2] (2) was selected for preliminary MOCVD experiments, which indicate a good suitability for the deposition of TiO2 thin films.