Zinc bis(acetylacetonate) Zn(acac)2

Zinc bis(acetylacetonate) (Zinc bis(2,4-pentanedionate) ) Zn(acac)2 (M = 263.61), is colorless needles or white powder melting at 135-138°C and subliming at 85°C/ 100 Torr . 

Zn(acac)2 has been widely used as a non-pyroforic zinc precursor for the growth of thin films of ZnO, ZnS, ZnGa2O4 etc. by MOCVD and ALD.

Zn(acac)2 for metallic Zn CVD

Zn(acac)2 has been applied for the deposition of nanometric Zn dots using near-field optical chemical vapor deposition (NFO-CVD), a method in which non-adiabatic photodissociation of precursor molecule takes place, even with visible light, as a consequence of the steep spatial gradient of the optical power of an optical near field. (in contrast to conventional optical CVD based on an adiabatic photochemical process requiring UV light to excite molecules from the ground electronic state to the excited state for dissociation). Zn(acac)2 hass generally low optical activity and therefore usually not used for conventional optical CVD. However, in the NFO-CVD non-adiabatic process, which can be explained using the exciton–phonon polariton model, enables the photodissociation of optically inactive Zn(acac)2 molecules. The process conditions included 70 mTorr Zn(acac)2 partial pressure in the CVD chamber, ultra-high purity argon (Ar) was used as a buffer gas [[i]]

[i]T. Kawazoe, K. Kobayashi and M. Ohtsu, Appl. Phys. B 84, 247–251 (2006)

Near-field optical chemical vapor deposition using Zn(acac)2 with a non-adiabatic photochemical process

Zn(acac)2 for ZnO CVD

Zinc acetylacetonate Zn(acac)2 was reported to be useful as CVD source for ZnO films [4]Growth rate of ZnO with Zn(acac)2 was reported to be 220nm/min at 600°C by atmospheric pressure CVD [27 in 296]

  Zn(acac)2 (+O2) for ZnO by low pressure MOCVD

 Zinc acetylacetonate Zn(acac)2, in combination with oxygen as co-reactant, has been applied for the growth of polycrystalline ZnO (0002) films by low-pressure MOCVD on Corning glass substrates at substrate temperatures 475-540 °C. Film grain size was as large as 200 nm according to AFM. The resistivity of the films strongly depended on the amount of dopant (f.e. Ga), and varied in the range 10−2 to 10−4 Ω cm; the lowest resistivity 6.9×10−4 Ω cm was obtained for the Ga-doped film (which had electron concentration 2.2×1020/cm3 and Hall mobility 40.9 cm2/V s). Room temperature PL revealed only a strong peak of near-band edge emission at 378.8 nm; low temperature (4.2 K) PL spectrum exhibited an emission from bound exciton of intrinsic donors. [[i]]

 Zn(acac)2 for ZnO by atmospheric pressure MOCVD 

Bis(acetylacetonato)-zinc Zn(acac)2 has been applied for the growth of transparent and uniform ZnO films (∼0.3 μm thick) by AP (atmospheric pressure) MOCVD on crown glass (CGW #200) substrates. Growth rate first remained constant at ca. 120 nm/min with increasing substrate temperature (Ts) till 550°C, but then increased abruptly to 220 nm/min at 600°C, further stopping increasing at substrate termperature > 600°C. The best crystallinity and maximum preferred orientation was obtained for the ZnO films grown at 550°C. [[ii]]

[i] Y Kashiwaba, K Sugawara, K Haga, H Watanabe, B.P Zhang, Y Segawa, Thin Solid Films, Volume 411, Issue 1, 22 May 2002, Pages 87-90 , “Characteristics of c-axis oriented large grain ZnO films prepared by low-pressure MO-CVD method”

[ii] Kiichiro Kamata, Junichi Nishino, Shigeo Ohshio, Kazunori Maruyama, Motohiko Ohtuki, J. Amer. Ceramic Society, 1994, Vol.77, Issue 2, pages 505–508, “Rapid Formation of Zinc Oxide Films by an Atmospheric-Pressure Chemical Vapor Deposition Method”

Zn(acac)2 (+H2O2, H2O, O2) for ZnO or ZnO(Al) by LP and AP MOCVD

Zinc acetylacetonate, in combination with various oxygen sources such as hydrogen peroxide (H2O2), water (H2O), or air, has been applied for the growth of transparent conducting ZnO films on glass substrates by atmospheric and low pressure CVD. It was determined that H2O and H2O2, which include hydrogen, were better oxygen sources than an O2-containing gas such as air. ZnO growth rate was controlled by the evaporation temperature of Zn(acac)2. For undoped ZnO thin films prepared at 550°C substrate temperature using H2O or H2O2, (4–6) × 10−3 Ω cm resistivity and > 80% average transmittance in the visible range were obtained. Al-doped ZnO films were prepared by low pressure (60 Torr) CVD at 350°C temperature using aluminium acetylacetonate (Al(acac)3) as dopant, the resistivity as low as 4.6 × 10−3 Ω cm was reached.[[i]]

[i] H. Sato, T. Minami, T. Miyata, S. Takata, M. Ishii, Thin Solid Films, Volume 246, Issues 1-2, 15 June 1994, Pages 65-70 Transparent conducting ZnO thin films prepared on low temperature substrates by chemical vapour deposition using Zn(C5H7O2)2 

Zn(acac)2 for ZnO(Al) by AP (NP) CVD

Bis(2,4-pentanedionato)zinc Zn(acac)2, in combination with Al(acac)3 as dopant source, has been applied as precursor for the preparation of aluminum-doped zinc oxide films ZnO(Al) as a transparent electrode material by a normal-pressure (atmospheric-pressure) CVD (NP-CVD) method. Transparent ∼0.3 μm ZnO(Al) films with a transmittance above 80% at a wavelength between 400 and 820 nm and minimum resistivity about 4.9 × 10−5Ω·m were grown on fused quartz substrates at 500°C. The increase of content of Al dopant caused the increase of optical band gap of the films from 3.3 to 3.6 eV. [[i]]

[i] Junichi Nishino, Shigeo Ohshio, Kiichiro Kamata, Journal of the American Ceramic Society, Volume 75, Issue 12, p 3469–3472, Dec 1992, Preparation of Aluminum-Doped Zinc Oxide Films by a Normal-Pressure CVD Method

Zn(acac)2 for ZnO(In) by AP CVD

Zn(acac)2 (vaporized at 115°C), with In(acac)3 as In source, has been applied for the growth of In-doped ZnO films on Si(100) at  at substrate temperature 525°C by AP CVD.

The growth rate was 3-7.2 µ/h, the prepared transparent conducting ZnO(In) films were characterised by XRD and SEM. [[i]]

[i] J. NISHINO, T. KAWARADA, S. OHSHIO, H. SAITOH, K. MARUYAMA, K. KAMATA, J. Mater. Sci. Lett, 1997, 16, p.629. “Conductive indium-doped zinc oxide films prepared by atmospheric-pressure chemical vapour deposition”

Zn(acac)2 for ZnS by AACVD

Zinc bis-acetylacetonate Zn(acac)2, in combination with thiourea or 1,1,3,3-tetramethylthiourea (dissolved in organic solvents) as S precursor, have been applied for the deposition of zinc sulphide ZnS thin films by CADT (AACVD), the results were compared with zinc dichloride (see corresponding ZnCl2 section. TG analysis was used for comparing of the volatility and stability of the precursors used; the rules for the selection of the starting compounds were deteremined. Homogeneous high density (96%) c-axis oriented ZnS layers having hexagonal columnar structure were obtained; luminescence was observed for the film prepared at temperature >500°C. The influence of the growth temperature, carrier gas flow, nozzle geometry and distance substrate to nozzle, of solvent and precursor volatility on the growth rate, homogeneity and film density was investigated. [5]

Zn(acac)2 for ZnMnS by CVD

ZnMnS nanobelts were prepared from Zn(acac)2and Mn precursor under H2S, photoluminescene in the range from blue-green to yellow-orange was obtained depending on the doping [39 in 278]

Zn(acac)2 for ZnGa2O4 CVD

Zinc acetylacetonate Zn(acac)2 in combination with gallium acetylacetonate Ga(acac)3 has been used as precursor for LPCVD of ZnGa2O4:Mn thin films as the emitting layer in thin‐film electroluminescent (TFEL) devices (quartz reactor, growth temperatures 700– 750 °C, pressure 6.7 kPa). The as‐deposited films were ZnGa2O4 crystallised in spinel structure. A green EL emission (with max luminances 0.7 -7.6 cd/m2) was realized in TFEL devices using as‐deposited ZnGa2O4:Mn thin films as the emitting layer and a thick BaTiO3 ceramic sheet as the insulating layer. Maximum luminance increased >600 cd/m2 in TFEL devices using ZnGa2O4:Mn thin films postannealed at ~1000°C; the improvement was attributed to an improvement in the crystallinity of the emitting layers upon annealing.[307]

Zn(acac)2 for (Zn,Ni)Fe2O4 CVD

Zinc acetylacetonate Zn(acac)2, in combination with Ni(acac)2 and Fe(acac)3 as co-precursors, has been used for for the preparation of epitaxial (Zn,Ni)FezO4 films on (1 00) MgO substrates by lowpressure CVD. Zn(acac)2 complex was evaporated at 79°C (compared to  157°C for Ni(acac)2  and 146 ° C for Fe(acac)3), and transported with N2 carrier gas (100sccm) to the deposition furnace, where growth happened under a pressure of 12torr, producing polycrystalline layers at 500 to 600°C and epitaxial films at 600 to 650°C temperatures. The saturation magnetization of 67 e.m.u, g-1 and the coercive force of 20 to 30 Oe was obtained for the epitaxial Zn0.4Ni0.6Fe204 film annealed at 600°C/ 60 min. [[i]]

[i] Hideaki Itoh, Toshiya Uemura, Hirofumi Yamaguchi and Shigeharu Naka, J. Mater. Sci. 24 (1989) 3549-3552 « Chemical vapour deposition of epitaxial Ni-Zn ferrite films by thermal decomposition of acetylacetonato complexes »

Zinc acetylacetonate hydrate Zn(acac)2·2H2O

Zinc acetylacetonate hydrate Zn(acac)2·2H2O (M = 263.61 (anhydr.basis)) has melting point  135-138°C, it has been characterized by FTIR, Raman

Zn(acac)2*2H2O for ZnO and ZnO-In2O3 by CVD

  Zinc acetylacetonate hydrate Zn(acac)2·2H2O was found to be useful MOCVD precursor for the preparation by CVD of highly transparent, conductive (based on film thickness) ZnO-In2O3 films. [[i]]

[i] Minami, T. et al. J. Vac. Sci. Technol. A 15, 1069, (1997)

       Zn(acac)2*H2O combined with C2H5OH as oxygen source has been applied for the growth of ZnO films by atmospheric pressure CVD (and compared to the ZnCl2-C2H5OH and Zn-H2O precursor systems). The structural and photoluminescence (PL) properties of the prepared layers were compared. For the Zn(acac)2*2H2O -C2H5OH system, the influence of the crystalline imperfection was observed on the XRD pattern and the PL spectrum. The accurate control of the O/Zn supply ratio is an important factor for controlling both defects and the concentration of the residual impurities, according to low temperature PL measurements. [[i]]

[i] Tomoaki Terasako, Keisuke Taira, Kouta Taniguchi, Masakazu Yagi, Sho Shirakata, Physica status solidi (c), Special Issue: 37th International Symposium on Compound Semiconductors (ISCS 2010), Volume 8, Issue 2, pages 509–511, February 2011, “Structural and optical properties of ZnO films grown by atmospheric- pressure CVD methods using different source materials”

Zn(acac)2*2H2O for (Zn,Ni)Fe2O4 CVD

High-crystallinity (Zn,Fe)Fe2O4 films and magnetic property measurements of these films have been obtained from Zn(acac)2*2H2O.[[i]]

[i] Mochizuki, S. et al. J. Phys. IV Colloq. 7(C1), 491, (1997)

Zinc acetylacetonate TMEDA adduct Zn(acac)2·(TMEDA)

Zinc bis(acetylacetonate) TMEDA adduct Zn(acac)2(TMEDA) has been applied for the growth of ZnO films by MOCVD [[i]]

[i] J.R. Babcock, A. Wang, N.L. Edleman, D.D. Benson, A.W. Metz, M.V. Metz and T.J. Marks, MRS Proceedings 2000 623 : 317 (12 pages), “Development and Implementation of New Volatile Cd and Zn Precursors for the Growth of Transparent Conducting Oxide Thin Films Via Mocvd.”

Zinc hexafluoracetylacetonate dihydrate diglyme adduct Zn(hfac)2(H2O)2·diglyme

Zinc hexafluoracetylacetonate dihydrate diglyme adduct

Zn(hfac)2(H2O)2·diglyme (along with other Zn(hfac)2·2H2O·polyether adducts) has been prepared by simple procedures with stoichiometric quantities of Zn(OH)2, Hhfac, and polyether (f.e.diglyme). The products have been characterized by elemental analysis, single crystal XRD, 1H and 19F NMR spectromttry, fast atom bombardment mass spectrometry, TGA/DSC, IR transmittance spectrometry and IR transmittance spectroscopy. An attempt to obtain water-free adduct was unsuccessful even using excess polyethers. X-ray single-crystal data of the Zn(hfa)2·2H2O·diglyme adduct show that the polyether does not coordinate to the metal center. Nevertheless, metrical data are indicative of bridging interactions involving the oxygen of one coordinated H2O molecule and the three oxygens of the diglyme. Very mild heating (37−51 °C) results in liquid compounds that, in turn, can easily be evaporated.

Zn(hfac)2(H2O)2·diglyme sublimes at 70-80°C/ 2-6 Torr [[i]]

 Zn(hfac)2(H2O)2·diglyme was reported to be applicable as precursor for CVD growth of ZnO films [4]

[i] Synthesis and Characterization of Novel Self-Generating Liquid MOCVD Precursors for Thin Films of Zinc Oxide, Chem. Mater., 2000, 12 (2), pp 548–554, DOI: 10.1021/cm991154k, Antonino Gulino, Francesco Castelli, Paolo Dapporto, Patrizia Rossi, Ignazio Fragalà

Zinc bis(hexafluoracetylacetonate) diglyme adduct Zn(hfac)2(diglyme)

 Anhydrous Zn(hfac)2·diglyme forms upon evaporation of Zn(hfac)2(H2O)2·diglyme due to competing H2O and diglyme ancillary ligation, as determined by gas-phase Fourier transform-IR measurements in vacuo.

Zn(hfac)2·diglyme has been applied as precursor for the deposition of ZnO films on fused SiO2 (quartz) substrates, in a low-pressure horizontal hot-wall MOCVD reactor. According to X-ray diffraction measurements, the layers consist of hexagonal (002) and (10l) oriented crystals. The transmittance of as grown ZnO films in the visible region is about 90%, as determined by UV−Vis spectroscopy. [[i]]

[i] Synthesis and Characterization of Novel Self-Generating Liquid MOCVD Precursors for Thin Films of Zinc Oxide, Chem. Mater., 2000, 12 (2), pp 548–554, DOI: 10.1021/cm991154k, Antonino Gulino, Francesco Castelli, Paolo Dapporto, Patrizia Rossi, Ignazio Fragalà

Zinc hexafluoracetylacetonate dihydrate Zn(hfac)2*2H2O

Zinc hexafluoracetylacetonate dihydrate Zn(hfac)2*2H2O has M = 515.52, melting at  155°C (with partial decomposiiton) , was characterized by FTIR.

Zn(hfac)2*2H2O has been applied for the growth of  highly crystalline (Zn,Fe)Fe2O4 ,films having good magnetic properties.

Zn(hfac)2*2H2O (in combinatioin with  Ga(acac)3 as co-precursoor) has been applied for the growth of ZnGa2O4:Mn thin films by LPCVD (quartz reactor, Tdep 700–750°C, press. 6.7 kPa)  as emitting layers in thin‐film electroluminescent (TFEL) device. As‐deposited ZnGa2O4:Mn films were spinel ZnGa2O4. Green EL emission (with max luminances 0.7 -7.6 cd/m2) for TFEL using as‐dep. ZnGa2O4:Mn films as the emitting layer.  Max luminance incr. >600 cd/m2 in TFEL devices using ~1000°C postannealed thin films;  attributed to improved crystallinity of the annealed emitting layers [[i]]

[i]T.Minami, Y. Kuroi, Sh.  Takata, Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, May 1996, Vol. 14 Issue:3, p. 1736 - 1740

Zinc bis(2-thenoyl-trifluoroacetonate)(TMEDA)

 Zinc bis(2-thenoyl-trifluoroacetonate) (N,N,N‘,N‘-tetramethyletilendiamine) adduct of Zn(tta)2·(TMEDA) has been synthesized in a single-step reaction. According to single-crystal XRD, the complex has mononuclear structure with a six-coordinated zinc ion. Mass-transport properties suitable for its application to MOCVD processes were determined when studying the adduct thermal behavior.

Zn(tta)2·(TMEDA) has been successfully applied as a MOCVD precursor for the  high quality ZnO films growth on (100) Si and quartz substrates. [[i]

[i] Graziella Malandrino, Manuela Blandino, Laura M. S. Perdicaro, Ignazio L. Fragalà, Patrizia Rossi, Paolo Dapporto, Inorg. Chem., 2005, 44 (26), pp 9684–9689, DOI: 10.1021/ic051175i A Novel Diamine Adduct of Zinc Bis(2-thenoyl-trifluoroacetonate) as a Promising Precursor for MOCVD of Zinc Oxide Films

Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)zinc Zn(thd)2

Zinc bis(2,2,6,6-tetramethylheptanedionate) Zn(thd)2 (M=431.92) has melting point 132-134°C, it has been characterized by FTIR.

Zn(thd)2 has been synthesized from the metal salt (zinc halide or acetate) by addition of Na(thd) or thdH  in a non-aqueous solvent such as an alcohol or hydrocarbon. Metallic contaminants in the metal salt raw material remained in the crude product, but were reduced to ppm levels by careful recrystallization.

Thermal behavior of Zn(thd)2 has been studied by TGA, which indicated that it evaporated in a similar temperature regime (190–230 °C) as Ni(thd)2, and Fe(thd)3, what is important for the application as precursor to deposit (Ni,Zn)Fe2O4 thin films by liquid injection MOCVD. [[i]]

[i] A.C. Jones, Chem. Vap. Deposition 1998, 4, No. 5, p.169-179, “MOCVD of Electroceramic Oxides: A Precursor Manufacturer’s Perspective”, http://is.muni.cz/el/1431/podzim2006/C7780/um/Read/2712635/MOCVD_precur_CVD98_169.pdf

Zn(thd)2 for ZnF2 CVD

Zn(thd)2, in combination with barium bis(1,1,1,5,5,5-hexafluoroheptene-2,4-dionato)barium2,5,8,11,14-pentaoxopentadecane adduct, Ba(hfa)2(tg) and NF3 as a fluorinating gas, has been applied as precursor for the growth of crystalline and amorphous ZnF2 and ZnF2-BaF2 thin-films by electron cyclotron resonance PECVD. Crystalline and transparent ZnF2 thin-films on CaF2(111) substrates with growth rates 0.2–0.8 μm/h. at 300° C substarte temperature. The ZnF2 layers prepared at lowest growth rate 0.2 μm/h were oriented along a [110] direction. Amorphous yellowish brown ZnF2 layers were obtained at 100°C substrate temperature, they had IR absorption bands due to contaminants. 60ZnF2·40BaF2 amorphous layers were colorless and contaminant-free. [[i]]

[i] Masanori Shojiya, Yoji Kawamoto, Akio Konishi, Hajimu Wakabayashi

Thin Solid Films, Volume 358, Issues 1-2, 10 January 2000, Pages 99-103

Zn(thd)2 for (Zn,Ni)FeO by liquid injection MOCVD

Zn(thd)2, in combination with Ni(thd)2 and Fe(thd)3 (all dissolved in tetrahydrofuran) has been applied as precursor for the liquid injection MOCVD growth of ZnO and ferrites ZnFeO and ZnNiFeO layers. The growth rates of the single metal oxide layers have been systematically determined as a function of substrate temperature in the range 300–650°; the ferrite layers were deposited at 500°C substrate temperature. The grown ferrite layers were polycrystalline with well-defined spinel crystal structures.[[i]]

[i]  P.A Lane, P.J Wright, M.J Crosbie,A.D Pitt, C.L Reeves, B Cockayne, A.C Jones, T.J Leedham, Journal of Crystal Growth, Volume 192, Issues 3–4, 1 September 1998, Pages 423–429, “Liquid injection metal organic chemical vapour deposition of nickel zinc ferrite thin films”

Zn(thd)2 for ZnO (Al) by aerosol-assisted MOCVD

Zn(thd)2 thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) , in combination with Al(thd)3 has been applied for the deposition of epitaxial Al-doped ZnO layers at 400 °C by an aerosol-assisted MOCVD technique at atmospheric pressure, obtaning film thickness (~ 70–1200 nm).  A solution of the precursor mixture (Zn + Al) in 1,2-dimethoxyethane (0.02 M in total) was coverted to aerosol via ultrasound (2.56 MHz), which was transported to the deposition zone by N2 + 10% O2 carrier gas. Depositions were carried out at 400 °C on sapphire-R substrates, and the films were subsequently cooled to RT in air. The as-grown films were annealed in a RTP furnace at 300–600 °C temperatures in various gas atmospheres (argon, Ar–H2 mixture, N2, O2, air, or vacuum), the change of the film microstructure, surface morphology, and electrical and optical properties after annealing was studied. The electrical properties of the films significantly degraded after annealing in oxygen and air, and improved when annealed in other gas environments (best resuls obtained in Ar-H2 mixture). The effect of the annealing on film electrical properties increased with the decrease in the film thickness. The film properties were nearly unchanged for further increases in the film thickness up to ~ 800 nm, whereas thicker films had degraded electrical properties due to partial cracking. [[i] ]

[i] S. Kuprenaite, A. Abrutis, V. Kubilius, T. Murauskas, Z. Saltyte, V. Plausinaitiene, Thin Solid Films, 599 (2016) 19–26, “Effects of annealing conditions and film thickness on electrical and optical properties of epitaxial Al-doped ZnO films”

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