Time-Resolved Studies Of Phase Transitions At Semiconductor Surfaces

1988 ◽  
Author(s):  
H. W. Tom ◽  
G. D. Aumiller ◽  
C. H. Brito-Cruz
Keyword(s):  
Phase Transitions ◽  
Semiconductor Surfaces ◽  
Time Resolved

Multiple phase transitions investigated by high-speed TEM

1990 ◽  
Vol 48 (4) ◽  
pp. 550-551
Author(s):  
Oleg Bostanjoglo ◽  
Peter Thomsen-Schmidt
Keyword(s):  
Phase Transitions ◽  
High Speed ◽  
Short Exposure ◽  
Semiconductor Film ◽  
Time Resolved ◽  
Short Exposure Time ◽  
Multiple Phase ◽  
Model Substance ◽  
History Of ◽  
Electron Image

Thin GexTe1-x (x = 0.15-0.8) were studied as a model substance of a composite semiconductor film, in addition being of interest for optical storage material. Two complementary modes of time-resolved TEM were used to trace the phase transitions, induced by an attached Q-switched (50 ns FWHM) and frequency doubled (532 nm) Nd:YAG laser. The laser radiation was focused onto the specimen within the TEM to a 20 μm spot (FWHM). Discrete intermediate states were visualized by short-exposure time doubleframe imaging /1,2/. The full history of a transformation was gained by tracking the electron image intensity with photomultiplier and storage oscilloscopes (space/time resolution 100 nm/3 ns) /3/. In order to avoid radiation damage by the probing electron beam to detector and specimen, the beam is pulsed in this continuous mode of time-resolved TEM,too.Short events ( <2 μs) are followed by illuminating with an extended single electron pulse (fig. 1c)

Ultra-fast Time-Resolved Electron Diffraction of Strongly Driven Phase Transitions on Silicon Surfaces

2009 ◽  
Vol 1230 ◽  
Author(s):  
Simone Möllenbeck ◽  
Anja Hanisch-Blicharski ◽  
Paul Schneider ◽  
Manuel Ligges ◽  
Ping Zhou ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Electron Diffraction ◽  
Structural Phase ◽  
High Energy ◽  
Silicon Surfaces ◽  
Fast Time ◽  
Time Resolved ◽  
Disorder Phase Transition ◽  
Pulse Pump

AbstractThe dynamics of strongly driven phase transitions at surfaces are studied by ultra-fast time-resolved reflection high energy electron diffraction. The surfaces are excited by an intense fs-laser pulse (pump) and probed by an ultra-short electron pulse with variable time delay. The order-disorder phase transition from a c(4×2) to a (2×1) of the bare Si(001) surface shows a transient decrease of the intensity of the c(4×2) spots which recovers on a time scale of a few hundred picoseconds indicating the excitation of the phase transition. On Si(111) a monolayer of Indium induces a (4×1) reconstruction which undergoes a Peierls like phase transition to a (8ד2”) reconstruction below 100 K. Upon laser excitation at a temperature of 40 K the phase transition was strongly driven. The (8ד2”)-diffraction spots instantaneously disappears, while the intensity of the (4×1)-spots increases. This increase of the (4×1) spot intensity excludes an explanation by the Debye-Waller-Effect and is evidence for a true structural phase transition at a surface.

A microsecond time resolved x-ray absorption near edge structure synchrotron study of phase transitions in Fe undergoing ramp heating at high pressure

2014 ◽  
Vol 115 (9) ◽  
pp. 093513 ◽  
Author(s):  
C. Marini ◽  
F. Occelli ◽  
O. Mathon ◽  
R. Torchio ◽  
V. Recoules ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Time Resolved ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

Femtosecond time-resolved spectroscopy of soft modes in structural phase transitions of perovskites

1994 ◽  
Vol 50 (13) ◽  
pp. 8996-9019 ◽  
Author(s):  
Thomas P. Dougherty ◽  
Gary P. Wiederrecht ◽  
Keith A. Nelson ◽  
Mark H. Garrett ◽  
Hans P. Jenssen ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Soft Modes

Metal deformation and phase transitions at extremely high strain rates

MRS Bulletin ◽  
2010 ◽  
Vol 35 (12) ◽  
pp. 999-1006 ◽  
Author(s):  
R. E. Rudd ◽  
T. C. Germann ◽  
B. A. Remington ◽  
J. S. Wark
Keyword(s):  
Phase Transitions ◽  
High Pressures ◽  
Materials Science ◽  
Strain Rates ◽  
Ambient Conditions ◽  
Time Resolved ◽  
Study Materials ◽  
Recent Developments ◽  
Metal Deformation ◽  
Kinetic Effects

The powerful lasers being constructed for inertially confined fusion generate enormous pressures extremely rapidly. These extraordinary machines both motivate the need and provide the means to study materials under extreme pressures and loading rates. In this frontier of materials science, an experiment may last for just 10s of nanoseconds. Processes familiar at ambient conditions, such as phase transformations and plastic flow, operate far from equilibrium and show significant kinetic effects. Here we describe recent developments in the science of metal deformation and phase transitions at extreme pressures and strain rates. Ramp loading techniques enable the study of solids at high pressures (100s of GPa) at moderate temperatures. Advanced diagnostics, such as in situ x-ray scattering, allow time-resolved material characterization in the short-lived high-pressure state, including crystal structure (phase), elastic compression, the size of microstructural features, and defect densities. Computer simulation, especially molecular dynamics, provides insight into the mechanisms of deformation and phase change.

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