Synchrotron X-ray Topography Studies of Dislocation Behavior During Early Stages of PVT Growth of 4H-SiC Crystals

The early stages of surface oxidation of biaxially textured Ni–W tapes were studied using thermodynamic calculations along with experimental tape oxidation at low P(O2). Tape phase and chemical composition, surface morphology, and roughness were examined using x-ray diffraction (XRD), energy-dispersive x-ray analysis (EDX), secondary ion mass spectroscopy (SIMS), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). For a Ni0.95W0.05 alloy tape, the precise position of the tape oxidation line in P(O2)–T coordinates was established. This line includes a break at T ≈ 650 °C that originates from the change of the W oxidation mechanism from internal oxidation to oxidation on a free surface accompanied by segregation of the alloy components in the tape near-surface region. The surface roughness of a polished tape increased drastically during internal oxidation of W; further tape oxidation did not affect the integral roughness parameters, but introduced numerous small (˜;100 nm) features on the tape surface comprising NiO precipitates.

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Early Stages of Oxidation of Clean Si(111)-7x7 and Si(100)-2x1 Surfaces Studied by In-Situ High Resolution X-Ray Photoelectron Spectroscopy

10.7567/ssdm.1996.b-4-2 ◽

1996 ◽

Author(s):

Josep L. ALAY ◽

Masataka HIROSE

Keyword(s):

High Resolution ◽

Photoelectron Spectroscopy ◽

X Ray ◽

Early Stages

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Structural development during the early stages of polymer melt spinning by in-situ synchrotron X-ray techniques

Polymer ◽

10.1016/s0032-3861(00)00232-9 ◽

2000 ◽

Vol 41 (25) ◽

pp. 8887-8895 ◽

Cited By ~ 88

Author(s):

J.M Schultz ◽

B.S Hsiao ◽

J.M Samon

Keyword(s):

Melt Spinning ◽

Polymer Melt ◽

Structural Development ◽

X Ray ◽

Early Stages

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Ion Beam Study of Early Stages of Growth of GaN films on Sapphire

MRS Proceedings ◽

10.1557/proc-743-l3.5 ◽

2002 ◽

Vol 743 ◽

Author(s):

Eugen M. Trifan ◽

David C. Ingram

Keyword(s):

Photoelectron Spectroscopy ◽

Ion Beam ◽

Ex Situ ◽

Crystallographic Axis ◽

In Situ Characterization ◽

X Ray ◽

Ion Channeling ◽

Stages Of Growth ◽

Early Stages

ABSTRACTAn innovative approach for in-situ characterization has been used in this work to investigate the composition, growth mode, morphology and crystalline ordering of the early stages of growth of GaN films grown on sapphire by MOCVD for substrate temperatures in the range of 450°C to 1050°C. We have performed in-situ characterization by Rutherford Backscattering Spectroscopy (RBS), Ion Channeling, X-ray Photoelectron Spectroscopy (XPS), and Low Energy Electron Diffraction. Ex-situ the films have been characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and thickness profilometry. The films have been grown in an in-house designed and build MOCVD reactor that is attached by UHV lines to the analysis facilities. RBS analysis indicated that the films have the correct stoichiometry, have variable thickness and for low substrate temperature completely cover the substrate while for temperatures 850°C and higher islands are formed that may cover as few as 5 percent of the substrate. From Ion Channeling and LEED we have determined the crystallographic phase to be wurtzite. The crystalline quality increases with higher deposition temperature and with thickness. The films are epitaxialy grown with the <0001> crystallographic axis and planes of the GaN films aligned with the sapphire within 0.2 degrees.

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