Nanoscale Heat Transport through Epitaxial Ultrathin Hetero Films: Bi(111)/Si(001) and Bi(111)/Si(111)

2012 ◽  
Vol 1404 ◽  
Author(s):  
Anja Hanisch-Blicharski ◽  
Simone Wall ◽  
Annika Kalus ◽  
Tim Frigge ◽  
Michael Horn- von Hoegen
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Linear Dependence ◽  
Decay Constant ◽  
Laser Pulses ◽  
Ultrafast Electron Diffraction ◽  
Cooling Process ◽  
Nanoscale Heat Transport ◽  
Acoustic Mismatch ◽  
Short Laser Pulses

ABSTRACTThe cooling process of ultrathin hetero films upon excitation with short laser pulses was studied for epitaxial Bi(111) films on Si(001) and Si(111) substrates by means of the Debye-Waller effect with ultrafast electron diffraction. From the exponential decay of the temperature, a cooling time constant was determined as a function of thickness for both substrates. For Bi/Si(111), a linear dependence between the decay constant and thickness was observed, even for 2.8 nm thin films , as predicted from the diffuse mismatch model (DMM) and the acoustic mismatch model (AMM). However, with Bi/Si(001), a significant deviation from this linear dependence was observed for film thicknesses below 5 nm.

scholarly journals LASER-INDUCED SURFACE ACOUSTIC WAVES FOR THIN FILM CHARACTERIZATION

2020 ◽  
Vol 27 ◽  
pp. 57-61
Author(s):  
Radim Kudělka ◽  
Lukáš Václavek ◽  
Jan Tomáštík ◽  
Sabina Malecová ◽  
Radim Čtvrtlík
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Young’S Modulus ◽  
Acoustic Waves ◽  
Young's Modulus ◽  
Surface Acoustic Waves ◽  
Laser Pulses ◽  
Data Application ◽  
Thin Film Characterization ◽  
Short Laser Pulses

Knowledge of mechanical properties of thin films is essential for most of their applications. However, their determination can be problematic for very thin films. LAW (Laser-induced acoustic waves) is a combined acousto-optic method capable of measuring films with thickness from few nanometers. It utilizes ultrasound surface waves which are excited via short laser pulses and detected by a PVDF foil. Properties such as Young’s modulus, Poisson’s ratio and density of both the film and the substrate as well as film thickness can be explored.Results from the LAW method are successfully compared with nanoindentation for Young’s modulus evaluation and with optical method for film thickness evaluation and also with literature data. Application of LAW for anisotropy mapping of materials with cubic crystallographic lattice is also demonstrated.

Influence of grain boundary weak links on the nonequilibrium response of YBaCuO thin films to short laser pulses

1994 ◽  
Vol 7 (4) ◽  
pp. 751-755 ◽  
Author(s):  
Gregory N. Gol'tsman ◽  
Ivan G. Goghidze ◽  
Pavel B. Kouminov ◽  
Boris S. Karasik ◽  
Alexei D. Semenov ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Laser Pulses ◽  
Weak Links ◽  
Short Laser Pulses

Nanoscale heat transport from Ge hut, dome, and relaxed clusters on Si(001) measured by ultrafast electron diffraction

2015 ◽  
Vol 106 (5) ◽  
pp. 053108 ◽  
Author(s):  
T. Frigge ◽  
B. Hafke ◽  
V. Tinnemann ◽  
B. Krenzer ◽  
M. Horn-von Hoegen
Keyword(s):  
Electron Diffraction ◽  
Heat Transport ◽  
Ultrafast Electron Diffraction ◽  
Nanoscale Heat Transport

Transient Cooling of Ultrathin Epitaxial Bi(111)-Films on Si(111) Upon Femtosecond Laser Excitation Studied by Ultrafast Reflection High Energy Electron Diffraction

2009 ◽  
Vol 1172 ◽  
Author(s):  
Anja Hanisch-Blicharski ◽  
Boris Krenzer ◽  
Simone Möllenbeck ◽  
Manuel Ligges ◽  
Ping Zhou ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Temperature Rise ◽  
Laser Fluence ◽  
Initial Temperature ◽  
Laser Excitation ◽  
Laser Pulses ◽  
High Energy ◽  
Time Resolved ◽  
Thermal Boundary Conductance ◽  
Short Laser Pulses

AbstractWith time resolved ultrafast electron diffraction the cooling process across the interface between a thin film and the underlying substrate was studied after excitation with short laser pulses. From the exponential decay of the surface temperature evolution a thermal boundary conductance of 1430 W/(cm2K) is determined for a 9.7 nm thin Bi(111) film on Si(111). A linear dependence between laser fluence and initial temperature rise was measured for film-thicknesses between 2.5 nm and 34.5 nm. The ratio of initial temperature rise and laser fluence for different film-thicknesses is compared to a model taking multilayer optics into account. The data agree well with this model.

Fast Photoresponse of Functionalized Pentacene and Anthradithiophene Thin Films

2007 ◽  
Vol 1003 ◽  
Author(s):  
Jonathan Day ◽  
Oksana Ostroverkhova ◽  
John Anthony
Keyword(s):  
Thin Films ◽  
Electric Field ◽  
Time Scales ◽  
Linear Dependence ◽  
High Performance ◽  
Continuous Wave ◽  
Charge Trapping ◽  
Laser Pulses ◽  
Glass Substrates ◽  
Polycrystalline Thin Films

AbstractWe present photoconductivity of high-performance functionalized pentacene and anthradithiophene thin films on time scales from picoseconds to many seconds after photoexcitation. The polycrystalline thin films were deposited from solution on glass substrates with patterned interdigitated aluminum electrodes. In studies of fast transient photoconductivity, the samples were excited with laser pulses of ~100 fs duration at a wavelength of 400 nm, and the photocurrent due to transport of photoexcited charge carriers was monitored using 50 GHz digital sampling oscilloscope. The photoconductivity at longer (milliseconds through seconds) time scales was investigated using continuous wave (cw) illumination and a source-delay-measure unit. Both experiments were performed under conditions of varied electric field strength, fluence and temperature. In all samples, we observed fast charge carrier photogeneration (<30 ps, limited by time resolution of our setup) followed by decay of the photocurrent over the period of 5-50 ns, depending on the material, due to charge trapping and recombination, linear dependence of the peak photoconductivity on the fluence and super-linear dependence of the peak photocurrent on the applied electric field.

scholarly journals Annealing of SnO_2 thin films by ultra-short laser pulses

2014 ◽  
Vol 22 (S3) ◽  
pp. A607 ◽  
Author(s):  
D. Scorticati ◽  
A. Illiberi ◽  
T. Bor ◽  
S.W.H. Eijt ◽  
H. Schut ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Pulses ◽  
Short Laser Pulses
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