Heating, Laser Irradiation and Passivation Study on the Light-Emitting Porous Silicon

1991 ◽  
Vol 256 ◽  
Author(s):  
H. C. Chen ◽  
W. Wang ◽  
K. N. Manjularani ◽  
L. C. Snyder ◽  
X. L. Zheng
Keyword(s):  
Laser Irradiation ◽  
Light Emission ◽  
High Vacuum ◽  
Laser Wavelength ◽  
Ultra High Vacuum ◽  
Ambient Atmosphere ◽  
Severe Problem ◽  
Light Emitting ◽  
Ecr Plasma ◽  
Plasma Passivation

ABSTRACTFor light-emitting porous Si there has been a severe problem with instability and degradation of the light emission. We report that a stabilization of the emission intensity and the peak energy can be achieved in air by a proper laser irradiation, In-situ photoluminescence measurements were performed to monitor the degradation and stabilization process under different conditions and parameters, such as laser power, laser wavelength and environment (ambient atmosphere of certain gas or ultra high vacuum). We found oxygen is the major cause for the emission degradation in this laser enhanced adsorption process, and the laser heating effect can be excluded. For a comparison we study the reversible thermal heating and quenching process. We also discuss microwave and ECR plasma passivation results.

scholarly journals Effect of Laser Irradiation on Emissivity of Flame-Generated Nanooxides

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2303
Author(s):  
Silvana De Iuliis ◽  
Roberto Dondè ◽  
Igor Altman
Keyword(s):  
Laser Irradiation ◽  
Light Emission ◽  
Energy Gap ◽  
Particle Temperature ◽  
Electron Excitation ◽  
Flame Spray ◽  
Energy Bands ◽  
Light Emitting ◽  
Spectral Behavior ◽  
The Difference

The application of pyrometry to retrieve particle temperature in particulate-generating flames strictly requires the knowledge of the spectral behavior of emissivity of light-emitting particles. Normally, this spectral behavior is considered time-independent. The current paper challenges this assumption and explains why the emissivity of oxide nanoparticles formed in flame can change with time. The suggested phenomenon is related to transitions of electrons between the valence and conduction energy bands in oxides that are wide-gap dielectrics. The emissivity change is particularly crucial for the interpretation of fast processes occurring during laser-induced experiments. In the present work, we compare the response of titania particles produced by a flame spray to the laser irradiation at two different excitation wavelengths. The difference in the temporal behavior of the corresponding light emission intensities is attributed to the different mechanisms of electron excitation during the laser pulse. Interband transitions that are possible only in the case of the laser photon energy exceeding the titania energy gap led to the increase of the electron density in the conduction band. Relaxation of those electrons back to the valence band is the origin of the observed emissivity drop after the UV laser irradiation.

Examination of the Silicon – Silicon Carbide Interface by Ultraviolet Photoemission Spectroscopy

1998 ◽  
Vol 512 ◽  
Author(s):  
C. Koitzscht ◽  
M. O'Brient ◽  
D. Johri ◽  
A. Stoltzt ◽  
R. Nemanicht
Keyword(s):  
Silicon Carbide ◽  
Valence Band ◽  
High Vacuum ◽  
Valence Band Maximum ◽  
Integrated System ◽  
Ultra High Vacuum ◽  
Photoemission Spectroscopy ◽  
Ambient Atmosphere ◽  
Silicon Silicon ◽  
State Feature

ABSTRACTPhotoemission spectroscopy (UPS) was used to investigate the interface properties of deposited silicon on hexagonal 6H-silicon carbide. SiC cleaned in Si flux from a molecular beam epitaxy (MBE) system was used for this study. All processes were accomplished in an ultra high vacuum integrated system that allowed all cleaning, deposition, and analysis to be completed without exposure to ambient atmosphere. Thicknesses of sub- to multiple monolayers were deposited and the valence band structure was investigated. The valence band maximum (VBM) was observed to shift for Si depositions greater than 1 monolayer. The VBM offset was determined to be 2.4eV for a layer of 60Å Si on SiC. Furthermore, the prominent surface state feature of the silicon carbide (0001)si surface is reduced after Si deposition. The results are discussed in terms of the electronic properties of the Si – SiC interface.

White-light-emitting magnetite nanoparticle–polymer composites: photonic reactions of magnetic multi-granule nanoclusters as photothermal agents

Nanoscale ◽  
2016 ◽  
Vol 8 (39) ◽  
pp. 17136-17140 ◽  
Author(s):  
Yu Jin Kim ◽  
Bum Chul Park ◽  
June Park ◽  
Hee-Dae Kim ◽  
Nam Hoon Kim ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Laser Irradiation ◽  
White Light ◽  
Magnetite Nanoparticles ◽  
Light Emission ◽  
White Light Emission ◽  
Magnetite Nanoparticle ◽  
Light Emitting

Magnetite nanoparticles combined with polymers produce white-light emission under multiphoton laser irradiation.

scholarly journals The Roughness-Enhanced Light Emission from Metal-Oxide-Silicon Light-Emitting Diodes Using Very High Vacuum Prebake

2002 ◽  
Vol 41 (Part 2, No. 3B) ◽  
pp. L326-L328 ◽  
Author(s):  
Min-Hung Lee ◽  
Kuan-Fu Chen ◽  
Chang-Chi Lai ◽  
Chee Wee Liu ◽  
Woei-Wu Pai ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Light Emitting Diodes ◽  
Light Emission ◽  
High Vacuum ◽  
Light Emitting ◽  
Metal Oxide Silicon ◽  
Very High

Interface dependent electrical properties of organic light emitting devices in ultra high vacuum

2000 ◽  
Vol 111-112 ◽  
pp. 307-310 ◽  
Author(s):  
Michael Kiy ◽  
Iris Gamboni ◽  
Urs Suhner ◽  
Ivan Biaggio ◽  
Peter Günter
Keyword(s):  
Electrical Properties ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Organic Light ◽  
Organic Light Emitting Devices

Surface Chemical Analysis of Nanoparticles for Commercial Products and Devices

2013 ◽  
Vol 1533 ◽  
Author(s):  
Marie-Isabelle Baraton
Keyword(s):  
Chemical Composition ◽  
Surface Chemistry ◽  
Surface Analysis ◽  
Surface Composition ◽  
High Vacuum ◽  
Surface Reactivity ◽  
Ultra High Vacuum ◽  
Ambient Atmosphere ◽  
Surface Chemical ◽  
Surface Chemical Composition

ABSTRACTAmongst the list of the measurands specific to nanoparticles, size and shape definitely matter but surface chemistry is also often cited. While it is now largely recognized that surface composition, structure and reactivity are perhaps the dominant parameters controlling properties of nanoparticles, surface chemistry is one of the key characteristics of nanoparticles which is seldom or inappropriately evaluated, as it has been identified by international organizations (such as ISO, BIPM or CEN). The usual techniques for surface analysis of materials often require ultra-high vacuum (UHV) conditions and are hardly applicable to nanoparticles. Moreover, because the surface chemical composition and reactivity are dependent on the environmental conditions, the results obtained under UHV cannot be extrapolated to nanoparticles in ambient atmosphere or dispersed in liquids.After an analysis of the stakes and challenges in the surface characterization of nanoparticles and a very brief overview of the usual techniques for surface studies, this paper presents the performance of Fourier transform infrared (FTIR) spectroscopy to investigate surface chemical composition, surface reactivity and surface functionalization of nanoparticles. As illustrating examples, the results of the FTIR surface analysis of different kinds of ceramic nanoparticles are discussed with regard to several fields of applications.

Multi-functionalization Of Silicon By Nanoparticles Through “Plug and Play” Approach

2001 ◽  
Vol 703 ◽  
Author(s):  
K. Prabhakaran ◽  
K.V.P.M. Shafi ◽  
A. Ulman ◽  
T. Ogino
Keyword(s):  
Optical Communications ◽  
Self Assembly ◽  
Light Emission ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Chemical Bonds ◽  
Surface Chemical ◽  
Full Width ◽  
Plug And Play ◽  
Si Wafer

ABSTRACTIn this paper, we demonstrate a “Plug and Play” approach, whereby externally synthesized nanoparticles of desired functions and size are incorporated into the semiconductor, followed by the manipulation of surface chemical bonds in order to achieve multiple functionality. Sonochemically synthesised Fe2O3 nanoparticles were introduced onto device quality Si wafers. On annealing the particle-treated Si wafer in ultra high vacuum, oxygen changes the bonding partner from Fe to Si and desorb as SiO at ∼ 760°C, leading to the formation of uniform sized Fe nanoparticles ( size ∼6-8 nm) on the surface and the sample shows ferromagnetic behaviour. More importantly, the particle treated Si exhibits light emission at wavelengths 1.57, 1.61 and 1.65 microns (full width at half maximum ∼ 20 meV). Emission in this wavelength range is crucial for optical communications and is highly desired from a Si based material. Further, oxidation of this material leads to the formation of a selective capping layer of SiO2. Thus, by manipulating the surface chemical bonds, we are able to introduce optical, magnetic, metallic and insulating functions to Si. Additionally, the particles exhibit self-assembly on a patterned Si surface. We believe that this approach is universal and the material developed here is compatible with the planar Si technology, bringing us closer to realization of Si based monolithic electronics.

Silicon epitaxy and pulsed laser irradiation in ultra-high vacuum

Vacuum ◽  
1983 ◽  
Vol 33 (9) ◽  
pp. 543-546 ◽  
Author(s):  
T. de Jong ◽  
F.W. Saris ◽  
J. Kistemaker
Keyword(s):  
Laser Irradiation ◽  
High Vacuum ◽  
Pulsed Laser ◽  
Ultra High Vacuum ◽  
Silicon Epitaxy ◽  
Pulsed Laser Irradiation

Light-Emitting Diodes Using Semiconducting Oligothiophenes

1993 ◽  
Vol 328 ◽  
Author(s):  
K. Uchiyama ◽  
H. Akimichi ◽  
S. Hotta ◽  
H. Noge ◽  
H. Sakaki
Keyword(s):  
Light Emitting Diodes ◽  
High Vacuum ◽  
Layered Structures ◽  
Hole Transport ◽  
Ultra High Vacuum ◽  
Transport Layer ◽  
Hole Transport Layer ◽  
Aluminum Electrode ◽  
Light Emitting ◽  
Carrier Recombination

ABSTRACTThe light-emitting diodes (LEDs) using semiconducting oligothiophenes, dimethylquater-thiophene (DMQtT, tetramer), dimethylquinquethiophene (DMQqT, pentamer) and dimethyl-sexithiophene (DMSxT, hexamer), have been investigated. These oligomers were deposited on ITO-coated glass in ultra high vacuum and an aluminum electrode was subsequently vacuum-deposited on top of the oligomers. These structures have the diode configuration with Schottky barrier between the oligomers and aluminum.The LED using DMSxT shows good rectifying feature with the rectifying ratio of 1500 at ±10V.Red-orange emission is clearly observed above 4V bias. In this LED, DMSxT acts not only as an emitting layer but also as a hole transport layer. We have also fabricated and studied alternate layered structures of DMSxT/DMQtT and DMSxT/DMQqT as the emitting layer. In these configurations, the carrier recombination can be modulated because both DMQtT and DMQqT have energy gaps wider than that of DMSxT.The quantum efficiencies (photons emitted per carriers injected) of the LEDs using DMSxT/DMQtT and DMSxT/DMQqT are about one hundred times and one thousand times larger than that of the LED solely based on DMSxT, respectively. These results indicate that the layered structures are advantageous in increasing quantum efficiency of the emission.

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