Plasma Cleaning and Nitridation of Sapphire Substrates for AlxGa1-xN Epitaxy as Studied by ARXPS and XPD

1997 ◽  
Vol 468 ◽  
Author(s):  
M. Seelmann-Eggebert ◽  
H. Zimmermann ◽  
H. Obloh ◽  
R. Niebuhr ◽  
B. Wachtendorf
Keyword(s):  
High Temperature ◽  
Photoelectron Spectroscopy ◽  
Short Range ◽  
Short Range Order ◽  
Thermal Treatments ◽  
Plasma Cleaning ◽  
Substrate Preparation ◽  
X Ray ◽  
Sapphire Substrates ◽  
Mocvd Reactor

ABSTRACTThe influence of plasma and thermal treatments on the structure and composition of sapphire (00–1) surfaces have been studied by hemispherically recorded x-ray photoelectron spectroscopy in view of substrate preparation for the epitaxy of GaN. Producing well-ordered surfaces, O2 plasma based treatments are found to efficiently remove surface contamination. AlN films with good short-range order are obtained by a simple high temperature nitridation step in the MOCVD reactor.

OBSERVATION OF PHASE TRANSITIONS AT THE (100) SURFACE OF Al-3 at.% Ag

1995 ◽  
Vol 02 (02) ◽  
pp. 141-145 ◽  
Author(s):  
E. WETLI ◽  
M. HOCHSTRASSER ◽  
D. PESCIA ◽  
M. ERBUDAK
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Photoelectron Spectroscopy ◽  
Short Range ◽  
Short Range Order ◽  
Elevated Temperatures ◽  
X Ray ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

In the bulk binary alloy Al-3 at.% Ag , Ag 2 Al precipitates are formed below 410°C which are reversibly dissolved at elevated temperatures. We have followed this phase transition at a (100) surface as a function of temperature by monitoring the bandwidth of the Ag 4d states in X-ray photoelectron spectroscopy. Since the bandwidth measures the coordination number of the emitting atoms, it directly reveals the short-range order of the Ag atoms at the surface. The measurements show that the dissolution of the Ag -rich clusters starts at temperatures at least 100 K below the bulk transition, and the observed hysteresis behavior is indicative of a first-order phase transition at the surface.

Studies of short-range order in amorphous Ge x Se100−x compounds by X-ray photoelectron spectroscopy

1994 ◽  
Vol 69 (2) ◽  
pp. 209-222 ◽  
Author(s):  
Marie-Luce Theye ◽  
Adriana Gheorghiu ◽  
Christiane Senemaud ◽  
Mohamed F. Kotkata ◽  
Kandil M. Kandil
Keyword(s):  
Photoelectron Spectroscopy ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
X Ray

Short-range order and electronic structure of radiation-damaged zircon according to X-ray photoelectron spectroscopy

2020 ◽  
Vol 47 (12) ◽  
Author(s):  
Yuliya V. Shchapova ◽  
Dmitry A. Zamyatin ◽  
Sergey L. Votyakov ◽  
Ivan S. Zhidkov ◽  
Andrey I. Kuharenko ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Photoelectron Spectroscopy ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
X Ray

Short-range order evolution in S-rich Ge–S glasses by X-ray photoelectron spectroscopy

2011 ◽  
Vol 357 (7) ◽  
pp. 1797-1803 ◽  
Author(s):  
R. Golovchak ◽  
O. Shpotyuk ◽  
S. Kozyukhin ◽  
M. Shpotyuk ◽  
A. Kovalskiy ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
X Ray

An X-ray and Neutron Scattering Study of the Structure of Zinc Vanadate Glasses

2001 ◽  
Vol 56 (6-7) ◽  
pp. 478-488
Author(s):  
Uwe Hoppe ◽  
Rainer Kranold ◽  
Emil Gattef ◽  
Jörg Neuefeind ◽  
David A. Keen
Keyword(s):  
Neutron Diffraction ◽  
Coordination Number ◽  
Short Range ◽  
Short Range Order ◽  
X Ray ◽  
Coordination Numbers ◽  
Gaussian Functions ◽  
Scattering Study ◽  
Neutron Scattering Study ◽  
Vanadate Glasses

Abstract The short-range order of vitreous V20 5 and of three (Zn0)Jt(V20 5)1_x glasses with x = 0.2, 0.4, and 0.5 is studied by X-ray and neutron diffraction experiments where the change of the contrast allows to resolve the V -0 and Z n -0 correlations. The V -0 and the Z n -0 first-neighbor peaks are approximat­ ed by several Gaussian functions. In case of vitreous V20 5 two obvious V -0 distances exist which are related with V 0 4 and V 0 5 units. With ZnO additions the V -O coordination number decreases from 4.4 in vitreous V20 5 to 4.0 in the metavanadate glass where the strongest decrease of the fraction of V 0 5 units is found for glasses of * < 0.2. Dominantly, the V 0 5 groups are linked with the neighboring units by comers. The Z n-0 coordination numbers of the modified glasses are about five with closest dis­ tances of = 0.200 nm.

scholarly journals Atomic Migration Studies with X-Ray Photon Correlation Spectroscopy

2014 ◽  
Vol 2 ◽  
pp. 73-94 ◽  
Author(s):  
Markus Stana ◽  
Manuel Ross ◽  
Bogdan Sepiol
Keyword(s):  
Low Temperatures ◽  
Short Range ◽  
Short Range Order ◽  
Photon Correlation Spectroscopy ◽  
Condensed Matter ◽  
Correlation Spectroscopy ◽  
Atomic Scale ◽  
Photon Correlation ◽  
X Ray ◽  
Amorphous Systems

The new technique of atomic-scale X-ray Photon Correlation Spectroscopy (aXPCS) makesuse of a coherent X-ray beam to study the dynamics of various processes in condensed matter systems.Particularly atomistic migration mechanisms are still far from being understood in most of intermetallicalloys and in amorphous systems. Special emphasis must be given to the opportunity to measureatomistic diffusion at relatively low temperatures where such measurements were far out of reach withpreviously established methods. The importance of short-range order is demonstrated on the basis ofMonte Carlo simulations.

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