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Featured researches published by John A. Glass.


Journal of Vacuum Science and Technology | 1992

Structures of selected boranes and carboranes

Sunwoo Lee; Peter A. Dowben; A.T. Wen; Adam P. Hitchcock; John A. Glass; James T. Spencer

Nido‐pentaborane(9) (B5H9), 1, nido‐2,3‐diethyl‐2,3‐dicarbahexaborane(8) [(C2H5)2C2B4H6], 2, nido‐decaborane(14) (B10H14), 3, closo‐1,2‐dicarbadodecaborane(12) (H2C2B10H10), 4, can be used as possible source compounds for boron and boron carbide thin film deposition. Inner shell electron energy‐loss spectroscopy (ISEELS) studies of the boron 1s and carbon 1s core excitations of gas phase species have been undertaken so as to characterize these molecular precursors at solid surfaces. The near edge structure of ISEELS provides a good ‘‘fingerprint’’ for the identification of these molecular species. A comparison is made between calculated [modified neglect of differential overlap (MNDO)] bond lengths for molecular clusters and the x‐ray or electron diffraction bond lengths, bond lengths determined from extended energy‐loss fine structure.


Journal of Electron Spectroscopy and Related Phenomena | 1994

Photoemission from gaseous and condensed molecular carborane cluster molecules

Dongjin Byun; Sunwoo Lee; Seong Don Hwang; Yong Feng Hu; G.M. Bancroft; John A. Glass; Jiandi Zhang; James T. Spencer; Jian Ma; Peter A. Dowben

Abstract The electronic structure of the nido -2,3-R 2 -2,3-dicarbahexaborane (R 2 C 2 B 4 H 6 where R is C 2 H 5 ) and closo -1,2-dicarbadodecaborane (C 2 B 10 H 12 ) have been studied by photoemission spectroscopy (PES). Photoemission spectra for condensed nido -2,3-diethyl-2,3-dicarbahexaborane(8) ((C 2 H 5 ) 2 C 2 B 4 H 6 ) exhibited features in good agreement with molecular orbitals assigned by modified neglect of differential overlap (MNDO) semiempirical theoretical calculations. Similar agreement can be demonstrated for the closo -1,2-dicarbadodecaborane.


MRS Proceedings | 1998

The Chemical Vapor Deposition of Zirconium Carbide onto Ceramic Substrates

John A. Glass; Nick Palmisiano; R. Edward Welsh

Zirconium carbide is an attractive ceramic material due to its unique properties such as high melting point, good thermal conductivity, and chemical resistance. The controlled preparation of zirconium carbide films of superstoichiometric, stoichiometric, and substoichiometric compositions has been achieved utilizing zirconium tetrachloride and methane precursor gases in an atmospheric pressure high temperature chemical vapor deposition system.


Journal of Physics and Chemistry of Solids | 1996

Chemical vapor deposition precursor chemistry. 5. The photolytic laser deposition of aluminum thin films by chemical vapor deposition

John A. Glass; Seong-Don Hwang; Saswati Datta; Brian W. Robertson; James T. Spencer

Thin films of very high purity aluminum were formed from the laser photolysis of trimethylamine alane (TMAA) using both ultraviolet (pulsed nitrogen) and visible (argon ion) laser irradiation on a variety of substrates including gold. Si (111), GaAs (110) and Teflon (PTFE). At thicknesses of up to 1 μm, nearly linear growth rates of 377 As -1 and 112 As -1 were observed. The formation of volatile species formed during the deposition of aluminum from TMAA was investigated by quadrupole mass spectrometry (QMS) of the reactant gas stream. The highest intensity post-deposition mass fragments were observed at m/z 58, 43 and 42 amu corresponding to (NC 3 H 8 ) + , (NC 2 H 5 ) + and (NC 2 H 4 ) + , respectively. These species arise from the dissociation and subsequent fragmentation of the trimethylamine ligand from the starting TMAA complex. Semi-empirical quantum chemical calculations (MNDO) for TMAA provided further support that photolysis of this precursor should result in principally ligand dissociation processes since the LUMO orbital is primarily an aluminum-nitrogen antibonding interaction. The deposited materials were also characterized by X-ray emission spectroscopy (XES), scanning electron microscopy (SEM), and Laser Microprobe Mass Analysis (LAMMA) techniques.


MRS Proceedings | 1990

The Deposition of Aluminum and Aluminum Boride Thin Films by Aluminaborane Cluster Compounds

John A. Glass; Shreyas S. Kher; Stephen D. Hersee; G. Ramseyer; James T. Spencer

The preparation of aluminum-containing thin film materials by MOCVD and MOMBE for use in III-V semiconductor materials, such as HEMT devices, is currently under active investigation. The preparation of uniform, conformal aluminum and boron containing thin film materials from the chemical vapor deposition (CVD) of aluminum borane cluster precursor compounds has been studied. A variety of substrates, deposition conditions and aluminaborane precursors have been explored and their effect on film composition, growth rate and thin film morphology has been investigated. The thermal depositions of aluminum and boron-containing thin films from aluminum borohydride, AI(BH 4 ) 3 , on copper, SiO 2 and GaAs are reported. Boron incorporation in the films vary depending on substrate temperature, aluminaborane flow and the presence or absence of a H 2 carrier. These films have been characterized by SEM, AES and XES.


Thin Solid Films | 1998

Epitaxial growth with phosphorus 3. Formation of indium phosphide thin films using cyclohexylphosphine, (C6H11)PH2, as the organophosphorus source compound

John A. Glass; James T. Spencer

Abstract The organophosphorus compound cyclohexylphosphine ((C6H11)PH2, PCH) with trimethylindium (TMI) cleanly forms thin films of crystalline indium phosphide (InP) under pyrolytic CVD conditions. These depositions are shown by Auger electron spectroscopy (AES) and other methods to be polycrystalline InP. Depositions were performed on both silicon (Si) and InP(100) substrates at temperatures and V/III ratios comparable to those employed in literature InP depositions with other phosphorus source compounds. The deposited materials were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), AES and X-ray thin film diffraction (XRD). The effect of precursor flow rates, V/III ratios, and substrate temperatures on the morphologies and compositions of the deposited InP materials was also investigated for the cyclohexylphosphine-based depositions


Thin Solid Films | 1998

Epitaxial growth with phosphorus 4. Application of dichloro-t-butylphosphine to CVD processes: The thermal chemical vapor deposition formation of copper phosphide thin films and etching of indium phosphide by dichloro-t-butylphosphine [1]

John A. Glass; James T. Spencer

Abstract The potential application of dichloro- t -butylphosphine (DCTBP) as a phosphorus source compound for InP growth is explored. Experiments employing DCTBP with trimethylindium were, however, unsuccessful in preparing InP thin films but rather resulted in the efficient etching of the InP substrate. An InP etching rate of 73.4 A/s was observed with an InP substrate temperature of approximately 600°C. A possible mechanism is presented to account for these observations. In addition, crystalline copper phosphide (Cu 3 P) thin films were formed from the thermal surface reaction of copper metal and DCTBP. The films are characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques.


Journal of Electron Spectroscopy and Related Phenomena | 1998

VALENCE BAND PHOTOEMISSION AND NEAR-EDGE CORE EXCITATION SPECTROSCOPY OF DI-T-BUTYLCHLOROPHOSPHINE

C.W. Hutchings; Adam P. Hitchcock; A.T. Wen; Seong-Don Hwang; John A. Glass; James T. Spencer; Y.-F. Hu; G.M. Bancroft; Peter A. Dowben

The electronic structure of di-t-butylchlorophosphine [(t-butyl) 2PCl] has been studied by photoemission spectroscopy (PES) and inner-shell electronic spectroscopy. The photoemission spectrum of (t-butyl) 2PCl exhibits features in good agreement with molecular orbital assignments based on modified neglect of differential overlap semiempirical calculations. The unoccupied electronic structure of (t-butyl) 2PCl has been investigated through P 2p, P 2s, Cl 2p, and C 1s core excitation spectra recorded by dipole-regime inner shell electron energy loss spectroscopy (ISEELS). The P 2p and P 2s spectra of (tbutyl) 2PCl exhibit features in common with PCl3 and P(CH3) 3, whereas the Cl 2p spectrum resembles that of PCl 3 and the C 1s spectrum resembles P(CH3) 3. Comparison of the photoemission and the ISEELS results emphasizes the local structural sensitivity of core excitation in contrast to the more extended picture of electronic structure provided by PES. q 1998 Elsevier Science B.V. All rights reserved


Materials Science and Engineering B-advanced Functional Solid-state Materials | 1995

Photo-assisted direct writing of conducting aluminum

Seong Don Hwang; Dongjin Byun; John A. Glass; Brian W. Robertson; James T. Spencer; Saswati Datta; Peter A. Dowben

We have succeeded in selective area deposition of aluminum films by ultraviolet photolytic decomposition of the organometallic complex trimethylamine alane, TMAA-AlH3(N(CH3)3)2. Both ultraviolet and visible light successfully photolysed the alane adduct and resulted in selective area deposition. The light sources exhibited different laser fragmentation mass spectra, suggesting somewhat different decomposition pathways.


MRS Proceedings | 1990

The Deposition of Nickel Boride Thin Films by Borane and Metallaborane Cluster Compounds

John A. Glass; Shreyas S. Kher; Yoon-Gi Kim; Peter A. Dowben; James T. Spencer

ABSTRACT The deposition of high purity and controlled stoichiometry metal boride thin-film materials has recentlv received considerable interest. Borane clusters and their corres~ondiin~ - metal complexes are currently Wig investigated in our laboratories for their utility as unique source materials for the formation of metallic boride thii films bv MOCVD. Variable composition nickel boride thin films ranging from 0.1 micron to several microns have been prepared. These new materials have been characterized by SEM, AES and XES. The magnetic properties of these new films have been investigated with torque magnetometry and magneto-optic Kerr effect magnetometry. The deposition of binary transition metal-main group thin-film materials of controlled stoichiometry is currently an area of intense research interest. Numerous techniques have been studied for the preparation of these materials including molecular beam epitaxy WE), sputtering and chemical vapor deposition (CVD) [I]. The control of the stoichiometry in multicomponent films prepared by chemical vapor deposition techniques has relied on varying the ratio of individual

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Brian W. Robertson

University of Nebraska–Lincoln

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Seong Don Hwang

University of Nebraska–Lincoln

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Seong-Don Hwang

University of Nebraska–Lincoln

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G.M. Bancroft

University of Western Ontario

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