A Study of CVD of Gallium Nitride Films by In Situ Gas-Phase UV Spectroscopy

ABSTRACTThe glyme adducts of bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionate)barium, Ba(hfac)2•glyme, are frequently employed as precursors in the MOCVD fabrication of HTSC thin films. The physical properties of these precursors can be modified by changing the glyme ligand in the barium complex. In this study, gas phase concentrations of two barium complexes as a function of purge time and bubbler temperature have been examined by in-situ UV spectroscopy. Also presented are the details of a UV spectrophotometric-based feedback control system designed to maintain constant gas phase concentration of 2,2,6,6-tetramethyl-3,5-heptadionate (thd) precursors, Cu(thd)2 and Y(thd)3, during MOCVD growth of mixed metal oxide films.

Download Full-text

MOCVD HTSC Precursor Delivery Monitored By UV Spectroscopy

MRS Proceedings ◽

10.1557/proc-415-149 ◽

1995 ◽

Vol 415 ◽

Cited By ~ 2

Author(s):

Brian J. Rappoli ◽

William J. DeSisto

Keyword(s):

Gas Phase ◽

Uv Spectroscopy ◽

Diagnostic Technique ◽

Chemical Vapor ◽

Test System ◽

Small Scale ◽

Mocvd Reactor ◽

Phase Concentration ◽

Scale Test

ABSTRACTUV spectroscopy has been used as an in situ diagnostic to measure the gas phase concentration of 2,2,6,6-tetramethyl-3,5-heptanedionate (thd) complexes of Ba, Cu and Y in metalorganic chemical vapor deposition (MOCVD) bubbler effluent. These precursors for MOCVD synthesis of YBa2Cu37−δ (YBCO) show marked instability in gas phase concentration as a function of time during bubbler purge. The UV diagnostic technique has been applied to both a small scale test system and a commercial scale MOCVD reactor.

Download Full-text

UV SPECTROSCOPY ON GAS PHASE Cu(I)-BIPYRIDYL COMPLEXES

Proceedings of the 70th International Symposium on Molecular Spectroscopy ◽

10.15278/isms.2015.ta09 ◽

2015 ◽

Author(s):

Shuang Xu ◽

J. Weber ◽

Casey Christopher

Keyword(s):

Gas Phase ◽

Uv Spectroscopy

Download Full-text

Luminescence properties of gallium nitride layers grown on silicon carbide substrates by gas-phase epitaxy in a chloride system

Semiconductors ◽

10.1134/1.1187206 ◽

1997 ◽

Vol 31 (5) ◽

pp. 523 ◽

Cited By ~ 5

Author(s):

A. S. Zubrilov

Keyword(s):

Silicon Carbide ◽

Gallium Nitride ◽

Gas Phase ◽

Luminescence Properties ◽

Chloride System ◽

Nitride Layers

Download Full-text

In Situ Observation of Electron-Beam-Induced Formation of Nano-Structures in PbTe

Nanomaterials ◽

10.3390/nano11010163 ◽

2021 ◽

Vol 11 (1) ◽

pp. 163

Author(s):

Iryna Zelenina ◽

Igor Veremchuk ◽

Yuri Grin ◽

Paul Simon

Keyword(s):

Electron Beam ◽

Gas Phase ◽

Threshold Current ◽

Threshold Current Density ◽

Atomic Scale ◽

In Situ Observation ◽

Nano Structures ◽

Transmission Electron ◽

Initial Crystal

Nano-scaled thermoelectric materials attract significant interest due to their improved physical properties as compared to bulk materials. Well-shaped nanoparticles such as nano-bars and nano-cubes were observed in the known thermoelectric material PbTe. Their extended two-dimensional nano-layer arrangements form directly in situ through electron-beam treatment in the transmission electron microscope. The experiments show the atomistic depletion mechanism of the initial crystal and the recrystallization of PbTe nanoparticles out of the microparticles due to the local atomic-scale transport via the gas phase beyond a threshold current density of the beam.

Download Full-text

An Atmospheric Origin for HCN-Derived Polymers on Titan

Processes ◽

10.3390/pr9060965 ◽

2021 ◽

Vol 9 (6) ◽

pp. 965

Author(s):

Zoé Perrin ◽

Nathalie Carrasco ◽

Audrey Chatain ◽

Lora Jovanovic ◽

Ludovic Vettier ◽

...

Keyword(s):

Chemical Composition ◽

Gas Phase ◽

Formation Process ◽

Upper Atmosphere ◽

Gas Mixture ◽

Space Probe ◽

Atmospheric Haze ◽

Formation And Evolution ◽

Haze Formation

Titan’s haze is strongly suspected to be an HCN-derived polymer, but despite the first in situ measurements by the ESA-Huygens space probe, its chemical composition and formation process remain largely unknown. To investigate this question, we simulated the atmospheric haze formation process, experimentally. We synthesized analogues of Titan’s haze, named Titan tholins, in an irradiated N2–CH4 gas mixture, mimicking Titan’s upper atmosphere chemistry. HCN was monitored in situ in the gas phase simultaneously with the formation and evolution of the haze particles. We show that HCN is produced as long as the particles are absent, and is then progressively consumed when the particles appear and grow. This work highlights HCN as an effective precursor of Titan’s haze and confirms the HCN-derived polymer nature of the haze.

Download Full-text