Laser-Ablated Particles From Porous Silicon

1994 ◽  
Vol 354 ◽  
Author(s):  
Hidehiko Nonaka ◽  
Shigeyuki Sekine
Keyword(s):  
Laser Ablation ◽  
Porous Silicon ◽  
Small Molecules ◽  
Ultrahigh Vacuum ◽  
Laser Deposition ◽  
Crystal Silicon ◽  
Ultraviolet Lasers ◽  
Time Of Flight Method ◽  
Kinetics Of ◽  
Source Materials

AbstractIn order to search for the possibility to synthesize materials with new functions by laser deposition using source materials consisting of characterized microstructures, the porous silicon was ablated in ultrahigh vacuum with ultraviolet lasers of fluence as low as a few Jem”2. The ablated particles were analyzed by the time of flight method and the main species detected were atoms and small molecules such as Si, SÍ2, and SiO. The kinetics of the laser ablation of porous silicon in comparison with crystal silicon was also studied.

scholarly journals Chemical and Light Inducible Epigenome Editing

2020 ◽  
Vol 21 (3) ◽  
pp. 998
Author(s):  
Weiye Zhao ◽  
Yufan Wang ◽  
Fu-Sen Liang
Keyword(s):  
Small Molecules ◽  
Expression Patterns ◽  
Cell Types ◽  
Epigenome Editing ◽  
Specific Targeting ◽  
Conditional Control ◽  
Cellular Behaviors ◽  
Different Cell Types ◽  
Kinetics Of ◽  
Epigenetic Research

The epigenome defines the unique gene expression patterns and resulting cellular behaviors in different cell types. Epigenome dysregulation has been directly linked to various human diseases. Epigenome editing enabling genome locus-specific targeting of epigenome modifiers to directly alter specific local epigenome modifications offers a revolutionary tool for mechanistic studies in epigenome regulation as well as the development of novel epigenome therapies. Inducible and reversible epigenome editing provides unique temporal control critical for understanding the dynamics and kinetics of epigenome regulation. This review summarizes the progress in the development of spatiotemporal-specific tools using small molecules or light as inducers to achieve the conditional control of epigenome editing and their applications in epigenetic research.

scholarly journals Oxygen in Complex Oxide Thin Films Grown by Pulsed Laser Deposition: a Perspective

2019 ◽  
Vol 33 (1) ◽  
pp. 205-212 ◽  
Author(s):  
Gertjan Koster ◽  
Dave H. A. Blank ◽  
Guus A. J. H. M. Rijnders
Keyword(s):  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Complex Oxide ◽  
Laser Deposition ◽  
Oxygen Stoichiometry ◽  
Oxide Thin Films ◽  
Film Synthesis ◽  
Kinetics Of ◽  
Oxidation Mechanisms

Abstract For thin film synthesis of complex oxides, one of the most important issues has always been how to oxidise the material. For a technique like pulsed laser deposition, a key benefit is the relatively high oxygen background pressure one can operate at, and therefor oxidation should be relatively straightforward. However, understanding the microscopic oxidation mechanisms turns out to be rather difficult. In this perspective, we give a brief overview of the sources of oxidation for complex oxide thin films grown by pulsed laser deposition. While it is clear what these sources are, their role in the kinetics of the formation of the crystal structure and oxygen stoichiometry is not fully understood.

Optical Properties of Free-Standing Ultrahigh Porosity Silicon Films Prepared by Supercritical Drying

1996 ◽  
Vol 452 ◽  
Author(s):  
J. Von Behren ◽  
P. M. Fauchet ◽  
E. H. Chimowitz ◽  
C. T. Lira
Keyword(s):  
Porous Silicon ◽  
Electrochemical Etching ◽  
Supercritical Drying ◽  
Silicon Films ◽  
Index Of Refraction ◽  
Free Standing ◽  
Crystal Silicon ◽  
Si Substrates ◽  
Type C ◽  
P Type

AbstractHighly luminescent free-standing porous silicon thin films of excellent optical quality have been manufactured by using electrochemical etching and lift-off steps combined with supercritical drying. One to 50 μm thick free-standing layers made from highly (p+) and moderately (p) Boron doped single crystal silicon (c-Si) substrates have been produced with porosities (P) up to 95 %. The Fabry-Pérot fringes observed in the transmission and photoluminescence (PL) spectra are used to determine the refractive index. At the highest P the index of refraction is below 1.2 from the IR to 2 eV. The absorption coefficients follow a nearly exponential behavior in the energy range from 1.2 eV and 4 eV. The porosity corrected absorption spectra of free-standing films made from p type c-Si substrates are blue shifted with respect to those prepared from p+ substrates. For P > 70 % a blue shift is also observed in PL. At equal porosities the luminescence intensities of porous silicon films made from p+ and p type c-Si are different by one order of magnitude.

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