ALUMINUM β-DIKETONATES
Aluminum tris(2,4-pentanedionate) (aluminum acetylacetonate) Al(acac)3
Density of Al(acac)3 was determined in [184]
Al(acac)3 has been used for the growth of Al2O3 by MOCVD[4]
Aluminium acetylacetonate (Al(acac)3) was applied as Al source and synthetic air as oxidant for the atmospheric pressure hot-wall MOCVD-growth of Al2O3 thin films on stainless steel substrates (this approach avoided the usage of an expensive vacuum system and expensive precursors, so low-cost deposition of the films can be achieved). The deposited Al2O3 layers were studied by FTIR, XRD, SEM and EDX. Deposition temperature ~600 K (~427°C) was necessary for film growth, and it could not be increased above 770 K (~500°C) due to the depletion of the precursor. Al2O3 films grown at 770 K (~500°C) were multicoloured, well adherent, amorphous, and stable up to 1070 K (~800°C). The deposited layers consisted mainly of Al and O, although the existence of Al hydroxides could not be excluded. Crystallisation and phase transformations were induced by the annealing at higher temperatures: at 1070 K (~800°C) γ-Al2O3 films were obtained and at 1380 K (~1100°C) α-Al2O3 was formed (however, these films were spalling).[i]
[i] Ch. Pflitsch, A. Muhsin, U. Bergmann, B. Atakan, Surf. Coat. Technology, 2006, Vol.201, Iss. 1–2, p.73-81, « Growth of thin aluminium oxide films on stainless steel by MOCVD at ambient pressure and by using a hot-wall CVD-setup », doi.org/10.1016/j.surfcoat.2005.10.036, https://www.sciencedirect.com/science/article/abs/pii/S0257897205011898
Aluminium acetylacetonate Al(acac)3 was applied as precursor for the deposition of carbonaceous crystalline
Al2O3 films on Si(100) by LP MOCVD. SIMS and XPS were used to study the elemental distribution and chemical nature of the C impurity in the films (which was attributed to the use of a Al(acac)3 as precursor). Spectroscopic ellipsometry was used to characterize
the layers; the photon energy range 1.5–5 eV was used to derive the pseudo-dielectric function of the Al2O3-containing films. The structural details of the specimens were extracted using multi-layer modelling using linear regression techniques and the
effective medium approximation; the excellent fit between the simulated and experimental optical data validated the empirical model for these MOCVD-grown Al2O3-containing
coatings.[i]
[i] M.P. Singh, G. Raghavan, A.K. Tyagi, S.A. Shivashankar, Bull. Mater. Sci., 2002, Vol.25, Iss.2, pp 163–168,https://www.ias.ac.in/article/fulltext/boms/025/02/0163-0168
« Carbonaceous alumina films deposited by MOCVD from aluminium acetylacetonate: a spectroscopic ellipsometry study », https://link.springer.com/article/10.1007/BF02706237
Al(acac)3 was used for the deposition of Al2O3 films on Si(100), stainless steel, and TiN-coated cemented carbide substrates by low-pressure metalorganic CVD
in the absence of an oxidant gas. The deposited layers appeared to be smooth, shiny, and blackish. Films deposited at temperatures as low as 600 °C contained small crystallites of κ-Al2O3, embedded in an amorphous matrix rich in graphitic C, according
to SIMS, XPS and TEM analyses. Surface morphology made up of spherulites was found by optical microscopy and SEM, it was suggested that film growth might involve a melting process. These observations were explained by possible nucleation and growth mechanism
involving the congruent melting clusters of precursor molecules on the hot substrate surface. The proposed mechanism was attempted to be verified experimentally.[i]
[i] M.P Singh, S.A Shivashankar, Surf. Coat. Technology, 2002, vol. 161, Iss. 2–3, p. 135-143, « Low-pressure MOCVD of Al2O3 films using aluminium acetylacetonate as precursor: nucleation and growth », https://doi.org/10.1016/S0257-8972(02)00470-X
Al(acac)3 was applied as precursor for the growth of Al2O3 films on Si(111) substrates at varying temperatures by MOCVD. Amorphous Al2O3 layers were obtained
at low temperatures (350–550 °C). The presence of crystalline Al2O3 was detected at temperatures increased >550°C, the crystallinity of the film increased at high temperatures (750–950°C), and 〈0 1 1〉κ-Al2O3 textured
layers were obtained at 950 °C.[i]
[i] S.K. Pradhan, Ph.J. Reucroft, Y. Ko, Surf. Coat. Techn., 2004, vol. 176, Iss.3, p.382-384, « Crystallinity of Al2O3 films deposited by metalorganic chemical vapor deposition », doi.org/10.1016/S0257-8972(03)00750-3,
Aluminum acetylacetonate Al(acac)3 was used as nontoxic and easy-to-handle precursor for the deposition of amorphous Al2O3 thin films on glass and Si(100)
substrates by a low-temperature atmospheric-pressure chemical vapor deposition (LT AP CVD). The substrate temperature could be lowered to 250 °C by the thermal decomposition of Al(acac)3 in air.[i]
[i] T. Maruyama, S. Arai, Appl. Phys. Lett. 60, 322 (1992), « Aluminum oxide thin films prepared by chemical vapor deposition from aluminum acetylacetonate »,
Aluminum tris(hexafluoroacetylacetonate) Al(hfac)3
Density of Al(hfac)3 was determined in [184]
Aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedionate) Al(thd)3
Al(thd)3 has been applied as precursors for the growth of Al2O3 by MOCVD[4]
Aluminum tris(2,2,6,6-tetramethyl-3,5-heptanedionate) Al(thd)3 was applied as Al precursor for the deposition of LaAlO3 films by volatile surfactant-assisted (VSA) MOCVD,
a new approach to the CVD of oxides with kinetically hindered diffusion, which is based on the film deposition in the presence of a volatile low melting point oxide (Bi2O3). Epitaxial and textured LaAlO3 films on various substrates were grown both by thermal
and VSA MOCVD. The LaAlO3 films deposited by VSA MOCVD demonstrated a significant improvement in crystalline quality and surface morphology. LaAlO3 films obtained in the presence of Bi2O3 did not contain Bi, and a significant increase (up to five times) of
the deposition rate was observed for LaAlO3 films deposited by VSA MOCVD compared to thermal MOCVD. [i]
[i] A. A. Molodyk, I. E. Korsakov, M. A. Novojilov, I. E. Graboy, A. R. Kaul, G. Wahl, Chem. Vap. Dep., 2000, Vol.6, Iss.3, p. 133-138, Volatile Surfactant‐Assisted MOCVD: Application to LaAlO3 Thin‐Film Growth, https://onlinelibrary.wiley.com/doi/abs/10.1002/(SICI)1521-3862(200006)6:3%3C133::AID-CVDE133%3E3.0.CO;2-G, doi.org/10.1002/(SICI)1521-3862(200006)6:3<133::AID-CVDE133>3.0.CO;2-G
Aluminium tris(2,2,6,6-tetramethyl-3,5-heptanedionate) Al(thd)3 (added to the Zn(thd)2 solution in 1,2-dimethoxyethane) was applied as Al precursor for the growth
of Al-doped ZnO films by aerosol-assisted MOCVD. The precursor solution nebulized by the ultrasound source (2.56 MHz), and the formed aerosol was transported by the N2 + O2 carrier gas to the deposition zone and AACVD deposition was performed at 350–600
°C. Hall measurements, XRD, SEM, AFM, UV–Vis and FT-IR spectroscopy was used to study the influences of the substrate, deposition temperature, and doping level on the layer structural, electrical and optical properties. Al-doped ZnO films had higher
resistivity compared to In-doped. Epitaxial Al-doped ZnO layers grown on R-plane sapphire demonstrated the best electrical properties; thus, the best ZnO(Al) films (~150–200 nm thick, grown on R-sapphire at 400 °C) demonstrated resistivity of 7–8×10−4
Ωcm, carrier concentration ~1.5 × 1020 cm− 3 and a relatively high carrier mobility ~50–60 cm2/Vs. The low resistivity of Al-doped films was mainly correlating with high carrier mobility. The optical transmittance (T) of the layers was high in both the visible (T > 90%) and the mid-IR spectral ranges (T≈ 90% at= 2.5 μm). The obtained Al-doped ZnO films are suitable for use as transparent electrodes in the IR optoelectronic devices applications due to their high transmittance
in the mid-IR spectral range. The carrier concentration markedly increased by the annealing of the Al-doped ZnO layers at 400°C in an Ar + H2 (10%) mixture for 30
min, resulting in the increase in the optical band gap (up to ~3.5 eV) and the decrease in film resistivity and transparency in the mid-IR spectral range. Annealed Al-doped ZnO films exhibited a resistivity of ~4 − 6×10− 4 Ω cm. [i]
[i] S. Kuprenaite, T. Murauskas, A. Abrutis, V. Kubilius, Z. Saltyte, V. Plausinaitiene, Surf. Coat. Technology, Vol. 271, 2015, p. 156-164, https://www.sciencedirect.com/science/article/abs/pii/S0257897214011967
Properties of In-, Ga-, and Al-doped ZnO films grown by aerosol-assisted MOCVD: Influence of deposition temperature, doping level and annealing, https://doi.org/10.1016/j.surfcoat.2014.12.052