MAGNESIUM β-DIKETONATES

Magnesium β-diketonates are useful precursors for MOCVD growth of Mg-containing layers such as MgO.

  The simplest β-diketonate, magnesium acetylacetonate Mg(acac)2 is trimeric in the solid state and thus has a very low vapor pressure. It has been used to grow MgO films using MOCVD28 and PECVD99 growth techniques.

  The bulkier magnesium bis(2,2,6,6-tetramethylheptanedionate) [Mg(tmhd)2]2 has lower nuclearity (dimeric), however it has a lower vapor pressure than other magnesium precursors because of its higher molecular weight.

  Magnesium bis(2,2,6,6-tetramethylheptanedionate) TMEDA adduct Mg(tmhd)2(TMEDA) has monomeric structure and due to its relatively higher volatility and good thermal stability is considered to be superior to [Mg(tmhd)2]2 as precursors for CVD applications. [4]

Magnesium bis(2,4-pentanedionate) (magnesium bis(acetylacetonate)) Mg(acac)2

    Magnesium bis(2,4-pentanedionate) (magnesium bis(acetylacetonate)) Mg(acac)2 is the conventional precursor for MOCVD of Mg-containing layers.

  The molecular structure of magnesium bis-acetylacetonate has been determined by synchronous gas-phase electron diffraction (GED) and mass spectrometric experiment and quantum mechanical calculations (HF/6-311+G(d,p), B3LYP/6-311+G(d,p), and MP2/6-311+G(d,p)). Both experimental and theoretical approaches resulted in the D2d symmetry structure with chelate rings located in perpendicular planes. Major structural parameters determined by GED experiment: bond distances rα(Mg–O)=1.966(4), rα(O–C)=1.279(2), rα(C–C′)=1.408(3), rα(C–Cm)=1.534(4) Å; valence angles angleα(O–Mg–O)=93.3(2), angleα(O–C′–C)=125.3(2), angleα(O–C–Cm)=116.2(4)° [180]

The decomposition of  Mg(acac)2 was studied to determine the optimal CVD temperature range. Above the melting temperature at 265°C, Mg(acac)2 is no longer stable. Decomposition model based on thermal analysis (TGA/ DSC) and IR and MS is following: the molecule splits giving a gaseous organic residue and a liquid (MgC5H6O2) which in turn gives rise to MgO at 450°C.[181]

The static sterochemistry in solution of Mg(acac)2 was investigated using 1H-NMR, it was found that Mg(acac)2 is polymeric in solution, in contrast to Mg(thd)2 which is monomeric. Chemical shift values favor a pseudo-tetrahedral D2d idealized structure.[182]

Proton magnetic resonance spectra of magnesium acetylacetonate in chloroform-d were studied, evidence for conformational equilibrium was observed. [183]

Density of Mg(acac)2 was determined in [184]

Mg(acac)2 for MgO by MOCVD

MgO films with (110) or (100) preferred orientation (NaCl-type structure) were grown at 400°C on glass substrates by PE MOCVD using Mg(acac)2 as a source material. Total pressure during the deposition as well as O2 to Mg gasphase ratio play a significant role in the preferred orientation of the films: (110)-oriented MgO films were obtained at low pressure of 0.15 Torr; increase of pressure to 1.0 Torr resulted in (100)-orientation of MgO films (with ratio of O2 to Mg source material kept constant). MgO films deposited at the high O/Mg ratios (1.61) had (100) orientation, while those deposited at low O/Mg ratios (0.97) were (110) oriented. No impurities in the oriented films was detected by RBS and AES. Films with (110) and (100) orientation were composed of closely packed columnar grains of diameter about 60 nm according to SEM. [185, 186, 187]

Mg(acac)2 and Mg(thd)2 were compared as precursors for the growth of thin films of MgO on Si(100) and c-plane sapphire substrates by MOCVD with oxygen as carrier gas. Films grown with Mg(acac)2 on c-plane sapphire above 500°C were polycrystalline with more dominant [110] and [100] orientation compared to [111]. In contrast, films grown with Mg(thd)2 on Si(100) at 600°C and on c-plane sapphire at 500°C were highly textured in the [111] direction, MgO film grown at lower temperature 350°C on Si(100) and then annealed at 520°C had no preferred orientation. [188]

Mg(acac)2 for MgO by spray pyrolysis / AACVD

Thin films of MgO (150 nm) were deposited by a spray pyrolysis method using ethanol-water solutions of Mg(acac)2 ultrasonically nebulized and thermally decomposed on to Si(111) and NaCl(100) substrates at 400–450°C. The microstructure of as-deposited MgO thin films was studied by XRD, SEM and TEM. [189]

The solution of Mg(acac)2 in isopropanol was used for the AACVD growth of MgO films on alumina polycrystalline substrates at 450°C (precursor aerosol was generated by ultrasonic atomization). The deposited film presented a smooth microstructure and a highly preferentially oriented structure with the (200) planes parallel to the substrate surface at a growth temperature of ~400°C. The thickness obtained reaches 10 μm, representing an efficient diffusion barrier on alumina for the deposition of thick films containing alkaline earth elements. [181]

Mg(acac)2 for MgTiO3 by MOCVD

 Magnesium acetylacetonate [Mg(acac)2] in combination with titanium isopropoxide [Ti(OiPr)4] were used as the Mg and Ti precursors, and O2 was the oxidizing gas, for the growth of ilmenite titanate MgTiO3 thin films on Si and SrTiO3 substrates by APMOCVD technique. Films deposited on Si were single-phase polycryst. MgTiO3, films on SrTiO3 substrate were (012) oriented. MgTiO3 films grown on SrTiO3(100) substrates at 650°C were transparent in the visible and exhibited a sharp absorption edge at 380 nm in the ultraviolet. Birefringence of MgTiO3 films was measured at room temperature by the cross-correlation method. [190]

Magnesium bis(acetylacetonate) hydrate Mg(acac)2(H2O)x

 Mg(acac)2(H2O)x for MgO by spray pyrolysis

Aqueous or alcoholic Mg(acac)2 solution was used for the preparation of MgO thin films (0.1-0.5 μm) by spray pyrolysis on Si(100), sapphire, and fused silica at temperatures between 400 and 550 °C. The precursor solution was ultrasonically nebulized, transported in flowing O2, and thermally decomposed on a substrate.  As deposited at 400-550°C films had poor crystallinity, but after annealing at 700 and 930°C in flowing oxygen (100) orientation occurred. [191] Strong (100) orientation was observed for MgO as deposited at 470°C on alumina soated sapphire from alcoholic solutions of Mg(acac)2 [192]

Magnesium bis(hexafluoroacetylacetonate)) Mg(hfac)2

Density of Mg(hfac)2 was determined in [184]

Magnesium bis(hexafluoroacetylacetonate) N,N,N’,N’-tetramethyethylenediamine adduct Mg(hfac)2(TMEDA)

Magnesium (II) bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionate) (N,N,N‘,N‘-tetramethylethylenediamine) adduct Mg(hfac)2(TMEDA) (hfac = hexafluoroacetylacetonate= (1,1,1,5,5,5-hexafluoro-2,4-pentanedionate) was synthesized, characterized and tested as a potential magnesium MOCVD precursor (being the best candidate in a series of low-melting, highly volatile, and thermally/air stable diamine-coordinated magnesium complexes: Mg(hfac)2(diamine), Mg(hfac)3H(diamine), and for comparison Mg(thd)2 and Mg(thd)2(TMEDA) ). The complexes were synthesized in a single-step aqueous reaction under ambient conditions, their molecular structures were determined by single-crystal XRD. These fluorinated diketonate magnesium complexes demonstrated much lower melting points and higher volatilities than previously reported Mg precursors for MgO thin film growth by MOCVD. Mg(hfac)2(TMEDA) has low melting point (61 °C) and excellent volatility and was successfully applied as precursor for the growth of MgO by MOCVD, resulting in the deposition of phase-pure MgO thin films at 550−675 °C temperatures on Corning 1737F glass, single-crystal Si, and single-crystal SrTiO3(100) and SrTiO3 (110). Highly (100)-oriented MgO films (XRD FWHM  3.1°) were obtained on amorphous glass. Epitaxial MgO thin films on both SrTiO3 substrates demonstrated excellent out-of-plane alignment (FWHM = 0.7 and 0.9°) and good in-plane alignment. The influence of growth temperature on the microstructure, surface morphology, and optical properties of MgO thin films was studied. [[i]]

 [i] Lian Wang, Y. Yang, J. Ni, Ch.L. Stern, T.J. Marks, Chem. Mater., 2005, 17 (23), pp 5697–5704, DOI: 10.1021/cm0512528, https://pubs.acs.org/doi/abs/10.1021/cm0512528 “Synthesis and Characterization of Low-Melting, Highly Volatile Magnesium MOCVD Precursors and Their Implementation in MgO Thin Film Growth”

Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)magnesium

Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)magnesium Mg(thd)2, or more precisely dimer [Mg2(thd)4]  was studied by various techniques - 1H NMR, MS, thermal analysis; the molecular structure molecular structure was determined by  single-crystal X-ray analysis: it crystallizes as a dimer [Mg2(thd)4]  where three oxygen atoms from three different thd ligands join the Mg atoms together.  [201]

[Mg(thd)2]2 for MgO films by MOCVD

MgO films were prepared on GaAs(100) substrates by LP MOCVD using Anhydrous bis(2,2,6,6-tetramethyl-3,5-heptanedionato)magnesium [Mg2(thd)4] as a precursor, and O2 as a carrier gas. Polycryst. MgO films at the substrate temperature of 300°C were [100] preferentially textured; [110] texture started to appear as the deposition temperature was increased. Deposition at 500 °C was found to induce breaking of the GaAs surfaces. [193]

 Polycrystalline MgO films having some [100] texture were grown using Mg(thd)2 on fused quartz substrates by MOCVD in a horizontal warm wall reactor. Growth rate of the film was about 0.4 μm/h at 740 °C. Films had a very smooth surface morphology and optical transparency with a refractive index 1.71.[195]

Mg(thd)2 was used as a precursor for the growth of MgO thin layers on glass, quartz, stainless steel and Ni by PECVD (parallel plate reactor with spacing 3 cm between 16cm diam. Al electrodes; plasma sustained by 13.56 MHz generator). Films grown at temperatures ≥673K (400°C) were (100) oriented (XRD). The influence of experimental parameters on growth rate and film properties was studied.[197]

MgO layers were grown on polished silicon (100) in a hot-wall pulsed MOCVD reactor using Mg(thd)2 precursor and O2 as oxidant in the substrate temperature range 350-450°C, source temperature 190-210°C. The morphology, structure and secondary electron emission of the films were investigated; AFM, ellipsometry, XRD characterisation performed. A detailed study of the precursor thermal parameters was carried out before deposition experiments to optimize the conditions for film growth. Temperature dependencies of vapour pressure were measured using the flow procedure and Knudsen's method with the mass spectrometric identification of the composition of the gas phase. The processes of Mg(thd)2 decomposition in vacuum, in oxygen and in water vapour were investigated by means of high-temperature mass spectrometry. The major products of precursor decomposition were established; the mechanism of its decomposition was proposed. [200]

MgO layers were grown by pulsed liquid-injection MOCVD technique in oxidizing conditions at atmospheric or sub-atmospheric pressure (103 Pa) using a single molecular source (Mg(thd)2). The grown magnesia films have NaCl-type structure according to XRD; films were also analysed by RBS, SEM, TEM, XPS. Among the various deposition conditions, substrate temperature and the oxygen flow rate were the most critical for determining growth rates, morphology and composition. [198]

Mg(thd)2 (0.05 M solution in monoglyme) was used for the pulsed LICVD growth on of MgO films as buffer layers for YBaCuO film depositon, on biaxially textured Ni alloys as substrates. [199]

Mg(thd)2 was used as a precursor for the solid source MOCVD growth of highly (100) textured thin films of MgO on r-plane sapphire and (100) SrTiO3 substrates at temperatures below 600°C. [196]

[Mg(thd)2]2 for MgO nanowires by MOCVD

Mg(thd)2 has been applied as precursor for the growth of  MgO nanowires by liquid-injection MOCVD at 600°C [[i], [ii], [iii}].  Mg(thd)2 precursor was dissolved in monoglyme at 0.02 mol/L; the total pressure was 10 Torr, with O2 partial pressure 2.4 Torr .

MgO nanowire growth was carried out on MgO (001) and Si (001) substrates (treated in HF acid in order to remove SiO2) at 600°C deposition temperature, using thin (typicall 2-3 nm) sputtered Au layer as catalyst;  the coated substrates were heated at 600°C/ 10 torr for 10 minutes (transforming continuous gold layer into islands with depending on the starting Au thickness. Nanowire morphology and dimensions were determined by TEM and field emission SEM; the crystalline structure of the wires was studied by XRD and electron diffraction. The presence of a roundshape gold nanoparticle at the tip of the wires (see Fig. 6(a)), pointed out to a vapor-liquid-solid (VLS) growth mechanism [108], with the not excluded contribution from a solid/vapor mechanism. The reactant flow rate was a critical parameter for the nucleation and growth at a surface. The growth direction both on MgO and Si substrates was along the [001] plane according to TEM, with MgO having cubic structure as confirmed by electronodiffractometry and HRTEM studies. On MgO, the wires grew epitaxially, being vertically aligned perpendicular to the substrate plane; in contrast, on Si (001) various orientations were observed. MgO nanowires exhibited a square-rod tapered shape with facets of {001} type on the sides; the bottom “diameter” of MgO nanowires was ~15 - 20 nm while the top diameter was lower (4 - 5 nm), the length was typically of 700 nm for 85 min deposition using an injection period of 3s. The wires dimensions depended on the starting Au catalyst, the temperature, the total pressure and the oxygen partial pressure. Thinner gold layer thickness (2 to 3 nm) was optimal , producing vertically aligned nanowires on MgO, while a thicker catalyst of ~4 nm hampered the vertical growth and produced wires with a much larger difference between bottom and top dimensions and with a larger bottom diameter (~ 35 -40 nm). It was possible to switch the growth from vertical to horizontal by decreasing the time at which the reactants were injected into the deposition chamber. For injection periods of 0.1 to 1 s, the wires grew along the substrate surface and had enhanced tapered shape. A small injection period corresponded to a high injection rate (with period of 0.1 s corresponding to 10 precursor droplets injected per second), which inhibited diffusion along vertical direction.

[i] C. Dubourdieu, I. Gelard, O. Salicio, G. Saint-Girons, B. Vilquin, G. Hollinger , International Journal of Nanotechnology, Iss.:  Vol. 7, Number 4-8 / 2010,  p. 320 – 347, http://www.cnano-raa.org/IMG/pdf_Dubourdieu-Oxide.pdf

“Oxides heterostructures for nanoelectronics”; and refs. therein

[ii] Y. F. Lai,1,a, P. Chaudouët,1F. Charlot,2I. Matko,1and C. Dubourdieu1

APPLIED PHYSICS LETTERS 94, 022904 , 2009, 0003-6951/2009/94, 2, /022904/3 94, 022904 “Magnesium oxide nanowires synthesized by pulsed liquid-injection metalorganic chemical vapor deposition”

[iii]YF. Lai, I. Matko, P. Chaudouët, F. Charlot, C. Dubourdieu, JNTE 2008, French Symposium on Emerging Technologies for Micro-nanofabrication, “Magnesium Oxide Nanowires Synthesized by MOCVD”

[Mg(thd)2]2 for MgO by ALD

Anhydrous bis(2,2,6,6-tetramethyl-3,5-heptanedionato)magnesium [Mg2(thd)4]  in combination with H2O2 as an oxidant was used for the growth of MgO thin films by atomic layer deposition. A rather constant growth rate of 0.10−0.14 Å/cycle was observed at 325−425 °C. [Mg2(thd)4]  crystallizes as a dimer where three oxygen atoms from three different thd ligands join the Mg atoms together.  [201]     Mg(thd)2 and O3 were used as precursors for the growth of MgO films on soda lime glass and Si(100) substrates by ALE at 180–450°C. Growth was surface-controlled in a narrow temperature range of 225–250°C with growth rates of 0.27 Å/cycle on glass and 0.22 Å/cycle on silicon. MgO films were characterized by XRD, RBS,  XPS and AFM.[202]

[Mg(thd)2]2 for MgO by electrostatic spray deposition

Mg(thd)2 dissolved in a organic solvent was used as precursor for MgO thin films deposition on SiO2/Si(100) and corning 7059 glass substrates by electrostatic spray deposition (ESD), a cheap deposition method suitable for large area coating. In case of use of pure THF as a solvent, a number of large particles appeared on the film surface due to homogeneous nucleation. Addition of 1-butyl or 1-octyl alcohol to THF, homogeneous nucleation was restricted and the density of the large particles significantly decreased. MgO films deposited at 673 K (400°C) had a (100)-preferred orientation according to XRD, independent of the type of solvent. Crystallized films on glass had high optical transmittance (>85%) in the visible range, according to FT-IR and spectroscopic photometry.    

MgO thin films were deposited on SiO2/Si(100) substrates by using electrostatic spray pyrolysis and Mg(thd)2 precursor. The growth rates of the films varied from 34 to 87 Å/min. X-ray diffraction analysis revealed that films grown at temperatures as low as 400500°C were crystalline and had preferred orientation to [100] plane perpendicular to the substrate surface. XPS and AES indicated low organic contamination. [204]

[Mg(thd)2]2 for MgF2 by ALD

Mg(thd)2, in combination with various fluorination agents, was used as a precursor for the ALD depositzion of magnesium fluoride MgF2 thin films, which is one of the most important ultraviolet (UV) transparent material widely used in optical applications in the large wavelength range.

Mg(thd)2, in combination with TiF4 as fluorinating agent, was used as as precursor for the growth of polycrystalline MgF2 films by ALD at 250–400°C. The refractive indices were between 1.34–1.42 and the permittivity 4.9. The growth rate was temperature dependent decreasing from 1.6 Å/cycle at 250 °C to 0.7 Å/cycle at 400 °C.The impurity levels were below 0.6 at.% in the films deposited at 350–400 °C. Films crystallinity, morphology, composition, thicknesses and refractive indices of the films were analyzed by XRD/XRR, TEM, AFM, FESEM, TOF-ERDA, and UV-vis spectrophotometry; electrical properties were measured as well. [205,206]

MgF2 thin films were grown at 225−400 °C on silicon substrates by ALD, using Mg(thd)2 as Mg source, and TaF5 as the fluorine precursor (instead of previously used HF and TiF4). Films were polycrystalline and grew in columnar fashion (Fig. ); film densities were close to bulk MgF2, good stoichiometry and low impurity levels were achieved. The refractive indices were between 1.36 and 1.38 at λ = 580 nm, the permittivity of the film grown at 300 °C was 5.0. The transmittance of the film deposited at 350 °C was good even in the deep UV range. MgF2 films were characterized by XRD, XRR, AFM, SEM, ERDA and spectrophotometry; optical and electrical properties of the films were studied. [207]

Mg(thd)2 for MgAl2O4 by MOCVD

Mg(thd)2, in combination with Al(acac)3 and O2 as precursors was used for the growth of MgAl2O4 films by combustion CVD at 850–1150°C [208].

[Mg(thd)2]2 for Pb(Mg,Nb)O by MOCVD

Mg(thd)2 in combination with Pb, Nb, Ti tetramethylheptanedionates was used as precursor for the growth of thin epitaxial films of Pb(Mg0.33Nb0.67)O3 (PMN) and Pb(Mg0.33Nb0.67)O3–PbTiO3 (PMN–PT), well known relaxor ferroelectric materials, on (001) SrTiO3 and SrRuO3/SrTiO3 single crystal substrates at 700°C by the solid-source MOCVD method. Pure PMN films were prepared using pre-mixed source material (5.5 eq. of Pb(thd)4?, 1 eq. of Mg(thd)2 and 2 eq. of Nb((thd)4?). Films were single phase with perovskite structure according to XRD. RBS showed that Pb/Mg/Nb/O was 18% /7% /13% /62%. Films of PMN–10%PT and PMN–20%PT films had dielectric constants 1200–1500 and 600–700, respectively. [209]

 [Mg(thd)2]2 for MgMnCoO by ALE

Mg(thd)2 ? as precursor was used for the growth of MgMnCoO layers on alumina by atomic layer epitaxy (ALE), using five to nine reaction cycles, each of which consisted of the reaction sequences of the corresponding metal β-diketonate and air. Layers were characterized by FTIR, XRD. [212]

            Mg(thd)2 was applied for the growth of thin films of Pb(Mg0.33Nb0.66)O3 (PMN), Ba-substituted PMN (BaxPb1-x(Mg0.33Nb0.66)O3) and Pb(Mg0.33Nb0.66)O3-PbTiO3 (PMN-PT) on Si and Pt/Ti/SiO2/Si substrates by MOCVD using ultrasonic nebulization of precursor solution.[210, 211]

Magnesium Bis(2,2,6,6-tetramethyl-3,5-heptanedionate) bis(aqua) adduct Mg(thd)2(H2O)2

Mg(thd)2(H2O)2 is a volatile compound – it sublimes at 117°C/2mbar, however with loss of coordinated water molecules yielding anhydrous Mg2(thd)4. It was applied as precursor for the CVD growth of thin magnesia layers.

Mg(thd)2(H2O)2 for MgO CVD

Mg(thd)2(H2O)2 complex dissolved in triglyme (0.1 g/ml concentration) was used as precursor for the deposition of thin MgO films at 773K (500°C), 1-2mbar pressure (basepress. 0.2-0.3 mbar) on glass, Si(100), Al2O3 substrates using plasma-assisted liquid injection chemical vapor deposition (PA LICVD). Depositions were performed in a 5:1 mixt. of ultra-high pure N2/O2 plasma with DC 0.18A, evaporator was kept at temperature of 473K (200°C) allowing precursor volatilisation. Composition and morphology of magnesia films was studied by XRD, SEM and EDX. [214]

Magnesium Bis(2,2,6,6-tetramethyl-3,5-heptanedionate) (N,N,N′,N″,N″-pentamethyldiethylenetriamine) adduct Mg(thd)2(pmdien)

Mg(thd)2(pmdien) is volatile and was considered as potential CVD precursor for MgO films. It has been prepared from Mg(thd)2(H2O)2 and pmdien. The temperature dependence of equilibrium vapor pressure (pe) - T data yielded a straight line when log pe was plotted against reciprocal temperature in the range of 360–475 K, leading to standard enthalpy of vaporization (ΔvapH°) values 67 ± 2 kJ/mol. [214]

Magnesium bis(2,2,6,6-tetramethyl-3,5-heptanedionate) TMEDA adduct Mg(tmhd)2(tmeda)

[Magnesium bis(2,2,6,6-tetramethyl-3,5-heptanedionate) mono(N,N,N′,N′-tetramethylethylenediamine) adduct Mg(thd)2(tmeda) is a relatively volatile compound (subliming at 120°C/5Torr) suggested to be superior for CVD applications compared to [Mg(thd)2]2 (which sublimes at ~200°C/5Torr) due to monomeric structure combined with sufficient thermal stability.[216]

Mg(thd)2(tmeda) was synthesized by the reaction of magnesium bis(2,2,6,6-tetramethyl-3,5-heptanedionate) dihydrate Mg(thd)2(H2O)2 with 1 equiv. of N,N,N′,N′-tetramethylethylenediamine (tmeda = Me2NCH2CH2NMe2) in hexane at RT. [214]

Mg(thd)2(tmeda) has standard enthalpy of sublimation 83.2 ± 2.3 kJ/mol and entropy of sublimation 263 ± 6.3 J/ mol·K determined from the temperature dependence of vapour pressure, performed using a horizontal dual arm single furnace thermogravimetric analyser as a transpiration apparatus. From the observed melting point depression DTA, the standard enthalpy of fusion (58.3 ± 5.2 kJ/mol) was evaluated, using the ideal eutectic behaviour of Mg(tmhd)2(tmeda) as a solvent, with Mg(acac)2 as a non-volatile solute. [217]

Mg(thd)2(TMEDA) for MgO growth by MOCVD

[Mg(thd)2(TMEDA)] was used as precursor for the growth MgO thin films by CVD o  sapphire and Si(100);  coatings were textured polycrystalline (by XRD); the chemical composition of the layers was determined by XPS. Complementary studies (TGA measurements and IR and NMR spectroscopy) revealed dissociation of TMEDA during evaporation at elevated tenperature, confirmed by the detection of both free TMEDA in the vapor phase and less volatile [Mg2(tmhd)4] as a residue after sublimation. The effect of this dissociation is an unwanted instability of Mg(thd)2(TMEDA) precursor sublimation rate during the CVD process. The constant deposition rate by simultaneously exploiting the good volatility of [Mg(thd)2(TMEDA)] was achieved by its in situ synthesis by supplying [Mg2(tmhd)4] precursor vapor simultaneously with a TMEDA enriched carrier gas. Laser reflectance interferometry (LRI) measurements confirmed good and constant deposition rate during the growth independently of the processing conditions (Fig.). [218]

Mg(thd)2(TMEDA) for Mg-doped ZrO2 by MOCVD

Mg(thd)2(TMEDA) was applied as Mg precursor for the stabilization of MOCVD-grown ZrO2 films in the cubic-fluorite phase. Colorless crack-free films well adherent to the fused quartz substrate were obtained at deposition temperature 500°C. Complete stabilization was achieved 12 to 30 at.% Mg. [162]

Magnesium bis(2,2,6,6-tetramethyl-3,5-heptanedionate) N,N’-dihexylethylendiamine adduct Mg(thd)2(dheda)

Magnesium Mg(thd)2(dheda) is monomeric liquid which can be distilled at 72°C/27mTorr. It produces magnesium oxides films by CVD with oxygen as oxidizer at substrate temperatures around 500°C [[43, 219]

Magnesium bis(2,2,6,6-tetramethyl-3,5-heptanedionate) phenantroline adduct Mg(thd)2(phen)

Magnesium bis(2,2,6,6-tetramethyl-3,5-heptanedionate) phenantroline adduct Mg(thd)2(phen) in combination with Al(acac)3 and O2 was applied as precursor for the deposition of MgAl2O4 thin films by volatile surfactant-assisted MOCVD at 850–950°C with. In this method, additional ‘Bi2O3’ or ‘PbO’ vapor was used to increase surface mobility of the reactants leading to enhanced film crystallinity [215]

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