Ammonolysis of reactive oxide precursors affords the vanadium(V) phase Ba(2)VO(3)N that is shown ... more Ammonolysis of reactive oxide precursors affords the vanadium(V) phase Ba(2)VO(3)N that is shown by X-ray and neutron powder diffraction and Raman spectroscopy to contain pseudotetrahedral VO(3)N(4-) anions. This is the first example of such species for the first transition series metals.
Highly boron-doped atomic concentration ; 10 cm conducting diamond films were grown on graphite s... more Highly boron-doped atomic concentration ; 10 cm conducting diamond films were grown on graphite substrates by microwave assisted vapor deposition from a gaseous feed of hydrogen and methane and solid boron. These diamond films of ca. 5 to 10 mm thickness composed of crystals of up to 10 mm size were characterized by both surface analytical techniques such as Raman Ž . Ž . spectroscopy, atomic force microscopy AFM , and scanning electron microscopy SEM , and electrochemical techniques. The reduction Ž . 3q 2q of Ru NH , the oxidation of chlorpromazine, and the reduction of Pb in aqueous media were studied in order to investigate the 3 6
High temperature p-type depletion-mode metal-insulator-semiconductor field-effect-transistors wit... more High temperature p-type depletion-mode metal-insulator-semiconductor field-effect-transistors with intrinsic diamond gates have been fabricated from thin film polycrystalline diamond. They have been successfully operated at 300°C with low leakage currents, and exhibit complete channel current pinch-off and modulation. A transconductance of 174 μS mm−1 has been measured, the highest reported value to date for this type of device.
... Polycrystalline diamond films for acoustic wave devices Michael D. Whitfield a Barbara Audic ... more ... Polycrystalline diamond films for acoustic wave devices Michael D. Whitfield a Barbara Audic , Colm M. Flannery b, Liam P. Kehoe b Gabriel M. Crean b, Colin Johnston , Paul R. Chalker ... 539 [14] L. Fayette, B. Marcus, M. Mermoux, L. Abello, G. Lucazeau, Diamond Relat. Mater. ...
Materials Science and Engineering B-advanced Functional Solid-state Materials, 1995
The wide band gap of diamond (5.5 eV) suggests that high temperature electronic device operation ... more The wide band gap of diamond (5.5 eV) suggests that high temperature electronic device operation will be achievable. The emergence of polycrystalline thin film diamond, grown by chemical vapour deposition methods, has made this prospect commercially interesting. Among the primary ...
Journal of The American Society for Mass Spectrometry, 2009
In this report, we present a prototype design of a quadrupole mass filter (QMF) with hyperbolic e... more In this report, we present a prototype design of a quadrupole mass filter (QMF) with hyperbolic electrodes, fabricated at the University of Liverpool using digital light processing (DLP), a low-cost and lightweight 3D rapid prototyping (RP) technique. Experimental mass spectra are shown for H 2 + , D 2 + , and He+ ions to provide proof of principle that the DLP mass filter is working as a mass analyzer in the low-mass range (1 to 10 amu). The performance of the DLP QMF has also been investigated for individual spectral peaks. Numerical simulations of the instrument were performed by coupling CPO and Liverpool QMS-2 programs to model both the ion source and mass filter, respectively, and the instrument is shown to perform as predicted by theory. DLP thus allows miniaturization of mass spectrometers at low cost, using hyperbolic (or other) geometries of mass analyzer electrodes that provide optimal ion manipulation and resolution for a given application. The potential of using RP fabrication techniques for developing miniature and microscale mass analyzers is also discussed.
Metalorganic chemical vapour deposition (MOCVD) is an attractive technique for the deposition of ... more Metalorganic chemical vapour deposition (MOCVD) is an attractive technique for the deposition of dielectric and ferroelectric oxide thin films such as ZrO 2 , HfO 2 , Hf-aluminate and -silicate, lanthanide oxides, Pb(Zr,Ti)O 3 and SrBi 2 Ta 2 O 9 , which have a variety of applications in microelectronic devices. In this paper the molecular design of a range of new oxide precursors is described. It is shown how the careful selection and design of precursor ligands, such as alkoxides and β-diketonates, leads to precursors with improved physical properties and significantly enhanced MOCVD performance.
Page 1. FEATURE ARTICLE Journal of MaterialsChemistry www .rsc.org/materials Some recent developm... more Page 1. FEATURE ARTICLE Journal of MaterialsChemistry www .rsc.org/materials Some recent developments in the MOCVD and ALD of high-k dielectric oxides{ Anthony C. Jones,*a{ Helen C. Aspinall,a Paul R. Chalker,b ...
J. Mater. Chem., 2005, 15, 3384-3387 DOI:10.1039/B507004J (Communication). Deposition of LaAlO 3 ... more J. Mater. Chem., 2005, 15, 3384-3387 DOI:10.1039/B507004J (Communication). Deposition of LaAlO 3 films by liquid injection MOCVD using a new [LaAl] single source alkoxide precursor. Troy D. Manninga, Yim Fun Looa ...
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2005
Lanthanide, or rare-earth oxides are currently being investigated as alternatives to SiO 2 as the... more Lanthanide, or rare-earth oxides are currently being investigated as alternatives to SiO 2 as the dielectric insulating layer in sub-0.1 m CMOS technology. Metalorganic chemical vapour deposition (MOCVD) and atomic layer deposition (ALD) are promising techniques for the deposition of these high-κ dielectric oxides and in this paper some of our recent research into the MOCVD and ALD of PrO x , La 2 O 3 , Gd 2 O 3 , Nd 2 O 3 and their related silicates are reviewed.
Lanthanum aluminate has been deposited for the first time by liquid injection atomic layer deposi... more Lanthanum aluminate has been deposited for the first time by liquid injection atomic layer deposition (ALD) using a bimetallic alkoxide precursor, [LaAl(O i Pr) 6 ( i PrOH)] 2 with H 2 O as oxygen source. The ALD growth rate was constant in the temperature range 160300 °C, but ALD ...
Complexes of the early lanthanides with the donor-functionalized alkoxide ligand mmp (Hmmp ) HOCM... more Complexes of the early lanthanides with the donor-functionalized alkoxide ligand mmp (Hmmp ) HOCMe 2 CH 2 -OMe, 1-methoxy-2-methylpropan-2-ol) are excellent precursors for Metal Organic Chemical Vapor Deposition (MOCVD) and Atomic Layer Deposition (ALD) of lanthanide oxides; however, their coordination chemistry, which is the subject of this paper, is rather complex. Precursors for MOCVD and ALD of lanthanide oxides are prepared by the reaction of [Ln{N(SiMe 3 ) 2 } 3 ] with 3 equiv of the alcohol Hmmp in toluene in the presence of 1 equiv of tetraglyme and are indefinitely stable in solution. Reaction of [Ln{N(SiMe 3 ) 2 } 3 ] with 3 equiv of Hmmp in the absence of stabilizing Lewis bases gives complex condensed products with empirical formula [{Ln(mmp) 3-n } 2 O n ]. These condensed products show poor volatility and are unsatisfactory precursors for MOCVD or ALD of oxides. The cluster complex [La 3 -(µ 3 ,κ 2 -mmp) 2 (µ 2 ,κ 2 -mmp) 3 (mmp) 4 ] has been prepared by careful reaction of [La{N(SiMe 3 ) 2 } 3 ] with 4 equiv of Hmmp and has been characterized by single-crystal X-ray diffraction. Salt metathesis reactions using M(mmp) (M ) Li or Na) are unreliable routes to [Ln(mmp) 3 ]. Crystals of the heterometallic cluster complex [NaLa 3 (µ 3 -OH)(µ 3 ,κ 2 -mmp) 2 -(µ 2 ,κ 2 -mmp) 4 (mmp) 3 ] were isolated from the reaction of [La(NO 3 ) 3 (tetraglyme)] with 3 equiv of Na(mmp), and crystals of [Li(κ 2 -Hmmp)Pr(µ 2 ,η 2 -mmp) 4 )LiCl] were isolated from the reaction of PrCl 3 with 3 equiv of Li(mmp); both of these complexes have been characterized by single-crystal X-ray diffraction.
ZrO2, HfO2, La2O3 and their related silicates are candidates to replace SiO2 as the gate dielectr... more ZrO2, HfO2, La2O3 and their related silicates are candidates to replace SiO2 as the gate dielectric material for sub-0.1 μm CMOS technology, and metalorganic chemical vapour deposition (MOCVD) is an attractive technique for the deposition of these materials. However, there are problems associated with many of the existing Zr and Hf oxide precursors. In this paper, we describe the liquid
A ''single-source'' Sr-Ta heterometal alkoxide precursor, Sr[Ta(OEt) 5 (dmae)] 2 (dmae=OCH 2 CH 2... more A ''single-source'' Sr-Ta heterometal alkoxide precursor, Sr[Ta(OEt) 5 (dmae)] 2 (dmae=OCH 2 CH 2 NMe 2 ), has been used for atomic vapour deposition (AVD) of SrBi 2 Ta 2 O 9 (SBT). This single-source precursor is designed to alleviate the mismatch between conventional Sr and Ta sources. Strontium tantalate thin films were deposited on silicon using the Sr[Ta(OEt) 5 (dmae)] 2 , and the optimum temperatures for deposition of strontium tantalate with a Sr:Ta ratio of 0.5 was found to be $510 1C. Deposition of Bi-oxide films using Bi(mmp) 3 (mmp=OCMe 2 CH 2 OMe) indicates similar decomposition behaviour to the Sr-Ta alkoxide precursor, demonstrating its suitability as a complementary source of Bi for SBT. The co-incorporation of Bi and Sr within the SBT films is promoted through the deposition of bismuth oxide/strontium tantalate super lattices. After post-growth annealing the super lattices are converted to strontium bismuth tantalate thin films. r
This paper explores the use of nanostructured zinc oxide (ZnO) films as a compliant buffer layer ... more This paper explores the use of nanostructured zinc oxide (ZnO) films as a compliant buffer layer for the growth of gallium nitride (GaN) on silicon substrates. Thin films of ZnO have been deposited on silicon (1 1 1) substrates by liquid injection metalorganic chemical vapour deposition (MOCVD) using dimethyl zinc-tetrahydrofuran adduct and oxygen. The use of the adduct complex avoids prereaction between the dialkyl zinc complex and oxygen which has been observed elsewhere. ZnO films deposited by this method were stoichiometric and of high purity, with no detectable carbon contamination. Films were deposited over a temperature range 350-550 1C, and exhibited a nanowire-like morphology. Subsequent deposition of GaN layers grown by molecular beam epitaxy (MBE) on the ZnO film resulted in the transformation of the nanowires to gallium oxide, accompanied by virtually complete removal of zinc from the layer. A heteroepitaxially oriented (c-axis) GaN/gallium oxide/silicon structure was produced after the nitride deposition which consisted of characteristic columnar GaN with the GaN[0 0 0 1]||Si [1 1 1]. Selective area electron diffraction of the by-product oxide interlayer showed a polycrystalline-like behaviour that gave rise to a random azimuthal distribution of the GaN grains. r
Novel Mononuclear Alkoxide Precursors for the MOCVD of ZrO 2 and HfO 2 Thin Films. -As revealed b... more Novel Mononuclear Alkoxide Precursors for the MOCVD of ZrO 2 and HfO 2 Thin Films. -As revealed by single crystal XRD (VIa) crystallizes in the orthorhombic space group P2 1 2 1 2 1 with Z = 4 and compound (VIb) in the monoclinic space group P2 1 /n with Z = 4. The mononuclear complexes (IIIa, b) and (VIa, b) are excellent precursors for the MOCVD of ZrO 2 and HfO 2 thin films over a wide range of substrate temperatures. The compounds are significantly less air-sensitive than the commonly used alkoxide sources Zr(OtBu) 4 and Hf OtBu) 4 , making them less susceptible to decomposition in solution and during storage, and easier to handle and use in MOCVD. -(WILLIAMS, PAUL A.; ROBERTS, JOHN L.; JONES, ANTHONY C.; CHALKER, PAUL R.; TOBIN, NEIL L.; BICKLEY, JAMIE F.; DAVIES, HYWEL O.; SMITH, LESLEY M.; LEEDHAM, TIMOTHY J.; Chem. Vap. Deposition
Thin films of HfO 2 have been deposited by liquid injection metal-organic (MO)CVD using the new a... more Thin films of HfO 2 have been deposited by liquid injection metal-organic (MO)CVD using the new alkoxide precursor [Hf(dmop) 4 ] (dmop = 2-(4,4-dimethyloxazolinyl)-propanolate). The crystal structure of [Hf(dmop) 4 ] has been determined, and shows it to be a six-coordinate monomeric complex. [Hf(dmop) 4 ] is volatile and is significantly less reactive to air and moisture than simple Hf alkoxide complexes such as [Hf(O t Bu) 4 ]. The HfO 2 thin films were deposited over substrate temperatures ranging from 350 C to 650 C. Analysis by X-ray diffraction (XRD) shows that the films are amorphous at deposition temperatures of 400 C and below. At substrate temperatures above 450 C, the films adopt a monoclinic (a-HfO 2 ) phase with a fiber texture dependent upon growth temperature. Analysis by Auger electron spectroscopy (AES) shows that the films are nonstoichiometric and contain residual carbon (2.1 ± 11.6 at.-%) and nitrogen (0.4 ± 1.9 at.-%).
RSC Publishing Logo View PDF VersionView Previous ArticleView Next Article DOI:10.1039/ B305665C ... more RSC Publishing Logo View PDF VersionView Previous ArticleView Next Article DOI:10.1039/ B305665C (Paper) J. Mater. Chem., 2004, 14, 391-395. Deposition of hafnium silicate films by liquid injection MOCVD using a single source or dual source approach. ...
Ammonolysis of reactive oxide precursors affords the vanadium(V) phase Ba(2)VO(3)N that is shown ... more Ammonolysis of reactive oxide precursors affords the vanadium(V) phase Ba(2)VO(3)N that is shown by X-ray and neutron powder diffraction and Raman spectroscopy to contain pseudotetrahedral VO(3)N(4-) anions. This is the first example of such species for the first transition series metals.
Highly boron-doped atomic concentration ; 10 cm conducting diamond films were grown on graphite s... more Highly boron-doped atomic concentration ; 10 cm conducting diamond films were grown on graphite substrates by microwave assisted vapor deposition from a gaseous feed of hydrogen and methane and solid boron. These diamond films of ca. 5 to 10 mm thickness composed of crystals of up to 10 mm size were characterized by both surface analytical techniques such as Raman Ž . Ž . spectroscopy, atomic force microscopy AFM , and scanning electron microscopy SEM , and electrochemical techniques. The reduction Ž . 3q 2q of Ru NH , the oxidation of chlorpromazine, and the reduction of Pb in aqueous media were studied in order to investigate the 3 6
High temperature p-type depletion-mode metal-insulator-semiconductor field-effect-transistors wit... more High temperature p-type depletion-mode metal-insulator-semiconductor field-effect-transistors with intrinsic diamond gates have been fabricated from thin film polycrystalline diamond. They have been successfully operated at 300°C with low leakage currents, and exhibit complete channel current pinch-off and modulation. A transconductance of 174 μS mm−1 has been measured, the highest reported value to date for this type of device.
... Polycrystalline diamond films for acoustic wave devices Michael D. Whitfield a Barbara Audic ... more ... Polycrystalline diamond films for acoustic wave devices Michael D. Whitfield a Barbara Audic , Colm M. Flannery b, Liam P. Kehoe b Gabriel M. Crean b, Colin Johnston , Paul R. Chalker ... 539 [14] L. Fayette, B. Marcus, M. Mermoux, L. Abello, G. Lucazeau, Diamond Relat. Mater. ...
Materials Science and Engineering B-advanced Functional Solid-state Materials, 1995
The wide band gap of diamond (5.5 eV) suggests that high temperature electronic device operation ... more The wide band gap of diamond (5.5 eV) suggests that high temperature electronic device operation will be achievable. The emergence of polycrystalline thin film diamond, grown by chemical vapour deposition methods, has made this prospect commercially interesting. Among the primary ...
Journal of The American Society for Mass Spectrometry, 2009
In this report, we present a prototype design of a quadrupole mass filter (QMF) with hyperbolic e... more In this report, we present a prototype design of a quadrupole mass filter (QMF) with hyperbolic electrodes, fabricated at the University of Liverpool using digital light processing (DLP), a low-cost and lightweight 3D rapid prototyping (RP) technique. Experimental mass spectra are shown for H 2 + , D 2 + , and He+ ions to provide proof of principle that the DLP mass filter is working as a mass analyzer in the low-mass range (1 to 10 amu). The performance of the DLP QMF has also been investigated for individual spectral peaks. Numerical simulations of the instrument were performed by coupling CPO and Liverpool QMS-2 programs to model both the ion source and mass filter, respectively, and the instrument is shown to perform as predicted by theory. DLP thus allows miniaturization of mass spectrometers at low cost, using hyperbolic (or other) geometries of mass analyzer electrodes that provide optimal ion manipulation and resolution for a given application. The potential of using RP fabrication techniques for developing miniature and microscale mass analyzers is also discussed.
Metalorganic chemical vapour deposition (MOCVD) is an attractive technique for the deposition of ... more Metalorganic chemical vapour deposition (MOCVD) is an attractive technique for the deposition of dielectric and ferroelectric oxide thin films such as ZrO 2 , HfO 2 , Hf-aluminate and -silicate, lanthanide oxides, Pb(Zr,Ti)O 3 and SrBi 2 Ta 2 O 9 , which have a variety of applications in microelectronic devices. In this paper the molecular design of a range of new oxide precursors is described. It is shown how the careful selection and design of precursor ligands, such as alkoxides and β-diketonates, leads to precursors with improved physical properties and significantly enhanced MOCVD performance.
Page 1. FEATURE ARTICLE Journal of MaterialsChemistry www .rsc.org/materials Some recent developm... more Page 1. FEATURE ARTICLE Journal of MaterialsChemistry www .rsc.org/materials Some recent developments in the MOCVD and ALD of high-k dielectric oxides{ Anthony C. Jones,*a{ Helen C. Aspinall,a Paul R. Chalker,b ...
J. Mater. Chem., 2005, 15, 3384-3387 DOI:10.1039/B507004J (Communication). Deposition of LaAlO 3 ... more J. Mater. Chem., 2005, 15, 3384-3387 DOI:10.1039/B507004J (Communication). Deposition of LaAlO 3 films by liquid injection MOCVD using a new [LaAl] single source alkoxide precursor. Troy D. Manninga, Yim Fun Looa ...
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2005
Lanthanide, or rare-earth oxides are currently being investigated as alternatives to SiO 2 as the... more Lanthanide, or rare-earth oxides are currently being investigated as alternatives to SiO 2 as the dielectric insulating layer in sub-0.1 m CMOS technology. Metalorganic chemical vapour deposition (MOCVD) and atomic layer deposition (ALD) are promising techniques for the deposition of these high-κ dielectric oxides and in this paper some of our recent research into the MOCVD and ALD of PrO x , La 2 O 3 , Gd 2 O 3 , Nd 2 O 3 and their related silicates are reviewed.
Lanthanum aluminate has been deposited for the first time by liquid injection atomic layer deposi... more Lanthanum aluminate has been deposited for the first time by liquid injection atomic layer deposition (ALD) using a bimetallic alkoxide precursor, [LaAl(O i Pr) 6 ( i PrOH)] 2 with H 2 O as oxygen source. The ALD growth rate was constant in the temperature range 160300 °C, but ALD ...
Complexes of the early lanthanides with the donor-functionalized alkoxide ligand mmp (Hmmp ) HOCM... more Complexes of the early lanthanides with the donor-functionalized alkoxide ligand mmp (Hmmp ) HOCMe 2 CH 2 -OMe, 1-methoxy-2-methylpropan-2-ol) are excellent precursors for Metal Organic Chemical Vapor Deposition (MOCVD) and Atomic Layer Deposition (ALD) of lanthanide oxides; however, their coordination chemistry, which is the subject of this paper, is rather complex. Precursors for MOCVD and ALD of lanthanide oxides are prepared by the reaction of [Ln{N(SiMe 3 ) 2 } 3 ] with 3 equiv of the alcohol Hmmp in toluene in the presence of 1 equiv of tetraglyme and are indefinitely stable in solution. Reaction of [Ln{N(SiMe 3 ) 2 } 3 ] with 3 equiv of Hmmp in the absence of stabilizing Lewis bases gives complex condensed products with empirical formula [{Ln(mmp) 3-n } 2 O n ]. These condensed products show poor volatility and are unsatisfactory precursors for MOCVD or ALD of oxides. The cluster complex [La 3 -(µ 3 ,κ 2 -mmp) 2 (µ 2 ,κ 2 -mmp) 3 (mmp) 4 ] has been prepared by careful reaction of [La{N(SiMe 3 ) 2 } 3 ] with 4 equiv of Hmmp and has been characterized by single-crystal X-ray diffraction. Salt metathesis reactions using M(mmp) (M ) Li or Na) are unreliable routes to [Ln(mmp) 3 ]. Crystals of the heterometallic cluster complex [NaLa 3 (µ 3 -OH)(µ 3 ,κ 2 -mmp) 2 -(µ 2 ,κ 2 -mmp) 4 (mmp) 3 ] were isolated from the reaction of [La(NO 3 ) 3 (tetraglyme)] with 3 equiv of Na(mmp), and crystals of [Li(κ 2 -Hmmp)Pr(µ 2 ,η 2 -mmp) 4 )LiCl] were isolated from the reaction of PrCl 3 with 3 equiv of Li(mmp); both of these complexes have been characterized by single-crystal X-ray diffraction.
ZrO2, HfO2, La2O3 and their related silicates are candidates to replace SiO2 as the gate dielectr... more ZrO2, HfO2, La2O3 and their related silicates are candidates to replace SiO2 as the gate dielectric material for sub-0.1 μm CMOS technology, and metalorganic chemical vapour deposition (MOCVD) is an attractive technique for the deposition of these materials. However, there are problems associated with many of the existing Zr and Hf oxide precursors. In this paper, we describe the liquid
A ''single-source'' Sr-Ta heterometal alkoxide precursor, Sr[Ta(OEt) 5 (dmae)] 2 (dmae=OCH 2 CH 2... more A ''single-source'' Sr-Ta heterometal alkoxide precursor, Sr[Ta(OEt) 5 (dmae)] 2 (dmae=OCH 2 CH 2 NMe 2 ), has been used for atomic vapour deposition (AVD) of SrBi 2 Ta 2 O 9 (SBT). This single-source precursor is designed to alleviate the mismatch between conventional Sr and Ta sources. Strontium tantalate thin films were deposited on silicon using the Sr[Ta(OEt) 5 (dmae)] 2 , and the optimum temperatures for deposition of strontium tantalate with a Sr:Ta ratio of 0.5 was found to be $510 1C. Deposition of Bi-oxide films using Bi(mmp) 3 (mmp=OCMe 2 CH 2 OMe) indicates similar decomposition behaviour to the Sr-Ta alkoxide precursor, demonstrating its suitability as a complementary source of Bi for SBT. The co-incorporation of Bi and Sr within the SBT films is promoted through the deposition of bismuth oxide/strontium tantalate super lattices. After post-growth annealing the super lattices are converted to strontium bismuth tantalate thin films. r
This paper explores the use of nanostructured zinc oxide (ZnO) films as a compliant buffer layer ... more This paper explores the use of nanostructured zinc oxide (ZnO) films as a compliant buffer layer for the growth of gallium nitride (GaN) on silicon substrates. Thin films of ZnO have been deposited on silicon (1 1 1) substrates by liquid injection metalorganic chemical vapour deposition (MOCVD) using dimethyl zinc-tetrahydrofuran adduct and oxygen. The use of the adduct complex avoids prereaction between the dialkyl zinc complex and oxygen which has been observed elsewhere. ZnO films deposited by this method were stoichiometric and of high purity, with no detectable carbon contamination. Films were deposited over a temperature range 350-550 1C, and exhibited a nanowire-like morphology. Subsequent deposition of GaN layers grown by molecular beam epitaxy (MBE) on the ZnO film resulted in the transformation of the nanowires to gallium oxide, accompanied by virtually complete removal of zinc from the layer. A heteroepitaxially oriented (c-axis) GaN/gallium oxide/silicon structure was produced after the nitride deposition which consisted of characteristic columnar GaN with the GaN[0 0 0 1]||Si [1 1 1]. Selective area electron diffraction of the by-product oxide interlayer showed a polycrystalline-like behaviour that gave rise to a random azimuthal distribution of the GaN grains. r
Novel Mononuclear Alkoxide Precursors for the MOCVD of ZrO 2 and HfO 2 Thin Films. -As revealed b... more Novel Mononuclear Alkoxide Precursors for the MOCVD of ZrO 2 and HfO 2 Thin Films. -As revealed by single crystal XRD (VIa) crystallizes in the orthorhombic space group P2 1 2 1 2 1 with Z = 4 and compound (VIb) in the monoclinic space group P2 1 /n with Z = 4. The mononuclear complexes (IIIa, b) and (VIa, b) are excellent precursors for the MOCVD of ZrO 2 and HfO 2 thin films over a wide range of substrate temperatures. The compounds are significantly less air-sensitive than the commonly used alkoxide sources Zr(OtBu) 4 and Hf OtBu) 4 , making them less susceptible to decomposition in solution and during storage, and easier to handle and use in MOCVD. -(WILLIAMS, PAUL A.; ROBERTS, JOHN L.; JONES, ANTHONY C.; CHALKER, PAUL R.; TOBIN, NEIL L.; BICKLEY, JAMIE F.; DAVIES, HYWEL O.; SMITH, LESLEY M.; LEEDHAM, TIMOTHY J.; Chem. Vap. Deposition
Thin films of HfO 2 have been deposited by liquid injection metal-organic (MO)CVD using the new a... more Thin films of HfO 2 have been deposited by liquid injection metal-organic (MO)CVD using the new alkoxide precursor [Hf(dmop) 4 ] (dmop = 2-(4,4-dimethyloxazolinyl)-propanolate). The crystal structure of [Hf(dmop) 4 ] has been determined, and shows it to be a six-coordinate monomeric complex. [Hf(dmop) 4 ] is volatile and is significantly less reactive to air and moisture than simple Hf alkoxide complexes such as [Hf(O t Bu) 4 ]. The HfO 2 thin films were deposited over substrate temperatures ranging from 350 C to 650 C. Analysis by X-ray diffraction (XRD) shows that the films are amorphous at deposition temperatures of 400 C and below. At substrate temperatures above 450 C, the films adopt a monoclinic (a-HfO 2 ) phase with a fiber texture dependent upon growth temperature. Analysis by Auger electron spectroscopy (AES) shows that the films are nonstoichiometric and contain residual carbon (2.1 ± 11.6 at.-%) and nitrogen (0.4 ± 1.9 at.-%).
RSC Publishing Logo View PDF VersionView Previous ArticleView Next Article DOI:10.1039/ B305665C ... more RSC Publishing Logo View PDF VersionView Previous ArticleView Next Article DOI:10.1039/ B305665C (Paper) J. Mater. Chem., 2004, 14, 391-395. Deposition of hafnium silicate films by liquid injection MOCVD using a single source or dual source approach. ...
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