Dimethyl Aluminum Research Articles

A novel bonding mode of a deprotonated synanti 2,2′-dipyridylamine ligand to dimethyl aluminium and dimethyl gallium. synthesis, characterization and x-ray crystal structure of Me 2Ga(DPA) (DPA2,2′-Dipyridylamine)

-The reaction of 2,2′-dipyridylamine with R 3M (R = CH 3, M = Ga, Al) gave the Lewis acid-base adducts Me 2Ga(dpa) and Me 2Al(dpa) (where dpa is 2,2′dipyridylamide). X-ray analysis showed an unusual structure of dpa - in the formation of a new anti-anti complex Me 2Ga(dpa) with extremely short bond distances Ga-N(1) [1.976(3) ] and Ga-N(2) [1.978(3) ]. The gallium atom is in a tetrahedral environment, coordinated to the deprotonated chelating ligand and two methyl groups. The bond distances N(3)-C(5) [1.345(4) ] and N(3)-C(6) [1.347(4) ] are almost identical. The bond angle N(l)-Ga-N(2) [92.0(1)°] is 17° smaller than, and C(12)-Ga-N(1) [109.5(2)°] is almost equal to, normal tetrahedral angles. These adducts are much less air- and moisture-sensitive than the metal trialkyl. The compounds were characterized by elemental analysis, NMR and mass spectroscopy. The conformation of the dipyridylamide ligand in the bidentate chelate complex is significantly different from that observed for other dipyridylamine complexes

Synchrotron radiation irradiation effects on low-temperature condensed layer of dimethyl aluminum hydride on SiO 2 surface

The synchrotron radiation (SR) irradiation effects on the low temperature condensed layer of dimethyl aluminum hydride (DMAH) were investigated by infrared reflection absorption spectroscopy, quadrupole mass spectroscopy with neutral desorbed species, and x-ray photoelectron spectroscopy (XPS). Both photo-thermal effect and photo-decomposition reaction are induced by SR irradiation. The DMAH dimer forms are changed to trimer by the photo-thermal effects in the condensed layer. The C/Al ratio which is an important parameter of the Al thin film deposition is substantially decreased from the value of the as-deposited layer by SR photo-decomposition but not so much by Mg K α irradiation decomposition.

Steric and electronic interactions between source gas and substrate surface during the Al-CVD/Al selective epitaxy process as investigated by quantum chemical calculations

We have performed quantum chemical calculations by semiempirical MNDO and by density functional theory (DFT) to rationalize the selection of an Al source gas for the selective Al-CVD/Al process. The electronic properties of Al(CH 3) n H 3− n , ( n = 0 to 3) and their adsorption complexes over representative aluminum metal clusters were calculated. Initially, the interaction of Al source gases with a representative Al metal was studied by both MNDO and DFT methods and the results were found to be qualitatively comparable. Further detailed calculations were performed by MNDO to understand the interaction of Al(CH 3) n H 3− n with larger cluster models of Al substrate as well as insulator silica surface. The results of the calculations indicate that the interaction energy between the substrate and the source are controlled by both steric and electronic factors. The steric factor favors the interaction of unsubstituted hydride, namely aluminum trihydride and the electronic factor favors the interaction of maximum substituted aluminum organic, namely trimethyl aluminum with the substrates. However, dimethyl aluminum hydride has the most favorable interaction energy with the Al metal, since it has the right combination of steric and electronic factors. The interaction energy of DMAH with chlorided silica surface is more favorable than the untreated silica surface.

Alkoxide precursors for controlled oxygen incorporation during metalorganic vapor phase epitaxy GaAs and AlxGa1−xAs growth

Controlled oxygen incorporation in GaAs using Al-0 bonding based precursors, dimethyl aluminum methoxide (DMALO) and diethyl aluminum ethoxide (DEALO), is presented in this investigation. A comparison study of oxygen incorporation kinetics between nominally undoped AlxGa1−xAs using trimethyl aluminum and DMALO-doped GaAs suggests that DMALO is one of the most important oxygen-bearing agents responsible for unintentional oxygen incorporation in AlxGa1−xAs. Controlled oxygen doping using DEALO is reported for the first time. Oxygen incorporation behavior, especially on the effect of the V/III ratio, was found to be quite different from the case of DMALO, mainly due to the differences between methyl- and ethyl-based growth chemistries. Physical, electrical, and optical properties of these oxygen-doped GaAs are also reported.

Controlled Impurity Introduction In CVD: Chemical, Electrical, and Morphological Influences

AbstractWe present here an overview of recent studies of the influence of oxygen doping on the electrical and structural properties of semiconductors grown through the metal organic vapor phase epitaxy (MOVPE) technique. In particular, we have measured the impact of oxygen introduction on several of the principal aspects of the growth process: incorporation, activation, and influence on the growing surface structure. The gas phase chemistry and dopant incorporation was investigated for two different precursors: dimethyl aluminum methoxide and diethyl aluminum ethoxide. The simple change in the structure of the oxygen source leads to significant changes in the oxygen incorporation behavior. Complementary studies of the gas phase decomposition of these oxygen sources have indicated that the decomposition mechanism is substantially different for these two sources leading to the change in incorporation behavior. The impact of the selective incorporation of oxygen at heterointerfaces has been studied here through the growth of superlattice structures. Glancing angle X-ray diffraction and atomic force microscopy measurements have shown that the incorporation of oxygen at the GaAs-to-AlxGaI-x As interface leads to modest increases in the average roughness of the heterointerface with more significant changes in the interfacial structure. The structure of this interfacial roughness was also studied through measurements of the diffuse X-ray scattering about a Bragg peak. Measurements of the component of the roughness which is correlated between the superlattice layers show significant changes with oxygen addition.

The reaction pathway for the growth of alumina on high surface area alumina and in ultrahigh vacuum by a reaction between trimethyl aluminum and water

It is demonstrated that it is possible to grow thin alumina films on an alumina substrate by the sequential adsorption of water and trimethyl aluminum (TMA) both on high-surface-area alumina and in ultrahigh vacuum (UHV) at room temperature. The presence of the resulting layer is demonstrated on high surface-area substrates using infrared spectroscopy and in UHV using electron energy-loss spectroscopy (EELS). The correspondence between the reaction on high surface-area alumina and in UHV allow the surface species to be identified using infrared spectroscopy on the high surface-area sample, and the kinetics to be measured in UHV. A film formation reaction mechanism is proposed that is consistent with the experimental results. It is suggested that TMA can react with hydroxylated alumina to form an adsorbed dimethyl aluminum species and evolve methane. This can further react with water to evolve further methane and leave adsorbed methyl groups. These react rather slowly with water resulting finally in the formation of a hydroxylated alumina surface.

Characterization of epitaxial GaAs and AlxGa1−xAs layers doped with oxygen

Intentional oxygen doping (≳1017 cm−3) of GaAs and Al0.30Ga0.70As epitaxial layers was achieved during metalorganic vapor phase epitaxy through use of an oxygen-bearing metalorganic precursor, dimethylaluminum methoxide (CH3)2AlOCH3. The incorporation of oxygen and very low levels of Al (AlAs mole fraction <0.005) in the GaAs layers leads to the compensation of intentionally introduced Si donors. Additionally, deep levels in GaAs associated with oxygen were detected. The introduction of dimethyl aluminum methoxide during AlxGa1−xAs growth did not alter Al mode fraction or degrade the crystallinity of the ternary layers, but did incorporate high levels of oxygen which compensated Si donors. The compensation in both GaAs and Al0.30Ga0.70As indicates that high resistivity buffer layers can be grown by oxygen doping during metalorganic vapor phase epitaxy.

Vibrational spectra of dimethyl aluminium hydride

The infrared and Raman spectra of dimethyl aluminium hydride and its partially deuterated isotopomers are reported and assigned. On the basis of variable temperature studies, coupled with isotope shifts and normal coordinate analysis, it is shown that the vapour phase infrared spectrum at room temperature may be interpreted as predominantly that of the dimer, with smaller amounts of trimer.

Growth and Characterization of Highly Oxygen-Doped GaAs

ABSTRACTHigh levels (≃ 1018cm-3) of oxygen were introduced into GaAs by using dimethyl aluminum methoxide (DMAlM0) as an oxygen-bearing precursor during metalorganic vapor phase epitaxy. Layers co-doped with oxygen and intentionally added silicon, both to concentrations of ≃ 1018 cm-3, were depleted of free carriers and had no measurable luminescence. Deep levels were present in layers grown with lower oxygen incorporation, but the compensation mechanism due to oxygen incorporation is not apparently tied to a specific defect level. The material with the electronic deep levels also possessed deep luminescence energy lines. All layers exhibited excellent surface morphology. For comparison, other layers were grown by introducing low levels of 02 and trimethyl aluminum during GaAs growth. The surface morphology of these layers was usually hazy and the layers did not exhibit the same well defined electrical and optical characteristics as the layers grown with DMAlMO.

The growth and characterization of AlGaAs using dimethyl aluminum hydride

The growth of AlGaAs by organometallic chemical vapor deposition has traditionally been done using trimethyl aluminum (TMA). The use of TMA, however, leads to a high level of carbon in the AlGaAs layers. In this study, we have investigated the use of dimethyl aluminum hydride (DMAH) as an alternative aluminum source. DMAH is a liquid at room temperature with a favorable vapor pressure of 2 Torr at 25°C. We report on the decomposition studies of DMAH and the growth and characterization of AlGaAs grown using the new compound. Preliminary low temperature PL spectra indicate that carbon acceptors are greatly reduced in layers grown under conditions similar to those used when growing with TMA. These results are supported by our finding the DMAH, when independently decomposed yields high purity aluminum metal, in contrast to TMA which yields aluminum carbides.

Alkynylaluminium compounds: V. Complexes and reaction mechanism of dimethylalkynylaluminium with ketones

Dimethyl(alkynyl)aluminium compounds and diethyl ether or acetone have been found to form 2/1 complexes, and structures are suggested for these. The mechanism of formation of the 2/1 complexes was studied. On the basis of the nature of the proposed structure of the 2/1 complex and that of the resulting mixed dimer Me 2Al(CCMe)(RO)AlMe 2 a modified six-centre transition state and rearrangement pathway are proposed.

Molecular orbital study of the bridge bonding in an electron deficient molecule [(CH3)2ALH

The electronic distribution in the AlH2Al bridge of the dimethyl aluminium hybride dimer was computed through ab initio SCF calculation. Comparison with diborane shows an increased role of the ionic Al+H 2 2− Al+ structures with respect to the usual covalent three-center bonds.

NMR studies on the reaction between methacrylonitrile and trimethylaluminum

AbstractThe reaction of MAN with AlMe3 was studied by the 13C‐ and 1H‐NMR spectral measurement. In the presence of an excess of AlMe3, it was found that a 1:1 complex of MAN and AlMe3 is initially formed and subsequently dimethyl(α‐methyl isopropylidene amino)aluminum is produced by the reaction of the complex with AlMe3. The isolated product was pale yellow crystal (mp 39–40°C). The kinetics of the reaction were also examined.

Spectroscopic evidence for pentahapto-cyclopentadienyl groups in solid dimethyl(cyclopentadienyl)aluminium

The IR and Raman spectra indicate that solid dimethyl(cyclopentadienyl)aluminium contains pentahapto-cyclopentadienyl rings of approximate D 5 h symmetry.

Molecular structure of dimethyl(cyclopentadienyl)aluminium monomer in the gas phase by electron diffraction

The cyclopentadienyl ring in gaseous monomeric AlMe2(C5H5) is bound to the metal atom in an asymmetric polyhapto fashion.

Stereochemistry of polynuclear compounds of the main group elements. XI. Dimethyl(methylthiol)aluminum, [(CH3)2AlSCH3]n, a new type of stereochemistry for an organoaluminum compound

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereochemistry of polynuclear compounds of the main group elements. XI. Dimethyl(methylthiol)aluminum, [(CH3)2AlSCH3]n, a new type of stereochemistry for an organoaluminum compoundD. J. Brauer and G. D. StuckyCite this: J. Am. Chem. Soc. 1969, 91, 20, 5462–5466Publication Date (Print):September 1, 1969Publication History Published online1 May 2002Published inissue 1 September 1969https://doi.org/10.1021/ja01048a011RIGHTS & PERMISSIONSArticle Views44Altmetric-Citations36LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (666 KB) Get e-Alerts Get e-Alerts

Organoaluminium compounds. XVIII. Mechanism of methyl group exchange between trimethylaluminium and dimethyl(phenylethynyl)aluminium

The exchange of methyl groups between trimethylaluminium and dimethyl- (phenylethyny1)aluminium has been studied by proton magnetic resonance spectro- scopy. The kinetics indicate that a monomer of trimethylaluminium attacks a dimer of dimethyl(phenylethynyl)aluminium in the rate-determining step.

A mechanism of interaction of triethyl aluminum with tetrabutyl titanium and the structure of resulting complexes

Trimethyl aluminum (TMA) is an important precursor used for metal-organic chemical vapor deposition (MOCVD) of most Al-containing structures, in particular of nitride structures. The reaction mechanism of TMA with ammonia is neither clear nor certain due to its complexity. Pyrolysis of trimethyl metal is the start of series of reactions, thus significantly affecting the growth. Experimental study of TMA pyrolysis, however, has not yet been conducted in detail. In this paper, a reflectron time-of-flight mass spectrometer is adopted to measure the TMA decomposition from room temperature to 800 °C in a special pyrolysis furnace, activated by soft X-ray from the synchrotron radiation. The results show that generation of methyl, ethane and monomethyl aluminum (MMA) indicates the start of the pyrolysis process. In the low temperature range from 25 °C to 700 °C, the main product is dimethyl aluminum (DMA) from decomposition of TMA. For temperatures larger than 700 °C, the main products are MMA, DMA, methyl and ethane.

Normal vibrations of dimers of aluminum trichloride, trimethyl aluminum and dimethyl aluminum chloride

The calculation of normal vibrations of Al 2Cl 6, Al 2Me 6 and Al 2Me 4Cl 2 has been made with a modified Urey—Bradley type potential. The force constants for Al 2Cl 6 and Al 2Me 6 have been calculated to agree with their observed frequencies. The frequencies of Al 2Me 4Cl 2 have been calculated with reference to the force constants transferred from those obtained for the two molecules. They are in satisfactory agreement with the observed values. The assigmnents of vibrational frequencies and the nature of ring modes are discussed on the basis of the calculations. The far infrared spectra of Al 2Me 6 and Al 2Et 6 in the region of 700-280 cm −1 were measured. The medium bands observed at 367 cm −1 for Al 2Me 6 and at 338 cm −1 for Al 2Et 6 have been assigned to one of the ring vibrations.

THE INFRARED SPECTRA OF TRIMETHYL ALUMINUM, DIMETHYL ALUMINUM CHLORIDE, METHYL ALUMINUM DICHLORIDE, METHYL TITANIUM TRICHLORIDE, DIMETHYL TITANIUM DICHLORIDE, AND SOME DEUTERIUM DERIVATIVES

The vapor phase infrared spectra to 300 cm−1 are discussed and assignments made for the compounds (CH3)6Al2, (CD3)6Al2, (CH3)4Al2Cl2, (CD3)4Al2Cl2, (CH3)2Al2Cl4, CH3TiCl3, CD3TiCl3, and (CH3)2TiCl2. The assignments differ significantly from those previously published, but are consistent throughout the series of aluminum compounds and with related spectra. The data are in agreement with a bridged structure for trimethyl aluminum of D2h or C2h symmetry and with a bridged structure of dimethyl aluminum chloride with chlorine bridging. The dimer (CH3)2Al2Cl4 is shown to exist in the trans configuration. Evidence is presented indicating that an impurity is commonly found in spectra of dimethyl aluminum chloride which is identified as the mixed dimer (CH3)3Al2Cl3, aluminum sesquichloride. A number of anomalies observed in the spectra of the methyl titanium compounds are pointed out and discussed.