Excimer laser cleaning, annealing, and ablation of β–SiC

1989 ◽  
Vol 4 (6) ◽  
pp. 1480-1490 ◽  
Author(s):  
Pehr E. Pehrsson ◽  
Ray Kaplan
Keyword(s):  
Excimer Laser ◽  
Photoelectron Spectroscopy ◽  
Ex Situ ◽  
Carbon Surface ◽  
Laser Exposure ◽  
Electron Loss ◽  
Bulk Heating ◽  
Surface Contaminants ◽  
Excimer Laser Irradiation

The effects of ArF excimer laser irradiation on β–SiC in UHV were examined for a variety of laser intensities and pulse densities. The samples were analyzed in situ with Auger and electron loss spectroscopies, and ex situ with x-ray photoelectron spectroscopy. With progressively higher laser intensities, the SiC surface was initially cleaned of carbon and oxygen surface contaminants, and the Si–LVV Auger lineshape changed from the oxide to the carbide. Still higher laser intensities then partially reordered the surface. A carbon surface layer developed, and the C-KLL lineshape transformed from carbidic to graphitic. Finally, the surface segregated into an almost pure Si layer and an underlying carbon-rich layer, followed by ablation and pitting. Bulk heating during laser exposure may enhance reordering of sputtered or implanted material.

On The Optimized Nucleation of Near-Single-Crystal Cvd Diamond Film

1995 ◽  
Vol 416 ◽  
Author(s):  
L. C. Chen ◽  
C. C. Juan ◽  
J. Y. Wu ◽  
K. H. Chen ◽  
J. W. Teng
Keyword(s):  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
Morphological Evolution ◽  
Present Report ◽  
Ex Situ ◽  
Nucleation Density ◽  
Induced Current ◽  
Current Time ◽  
Single Crystal Diamond

ABSTRACTNear-single-crystal diamond films have been obtained in a number of laboratories recently. The optimization of nucleation density by using a bias-enhanced nucleation (BEN) method is believed to be a critical step. However, the condition of optimized nucleation has never been clearly delineated. In the present report, a novel quantitative technique was established to monitor the nucleation of diamond in-situ. Specifically, the induced current was measured as a function of nucleation time during BEN. The timedependence of induced current was studied under various methane concentrations as well as substrate temperatures. The optimized nucleation condition can be unambiguously determined from the current-time plot. Besides the in-situ current probe, ex-situ x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were also used to investigate the chemical and morphological evolution. Characteristic XPS and AFM features of optimized nucleation is discussed.

In situ excimer laser irradiation as cleaning tool for solid phase epitaxy of laser crystallized polycrystalline silicon thin films

2013 ◽  
Vol 210 (12) ◽  
pp. 2729-2735 ◽  
Author(s):  
Ingmar Höger ◽  
Thomas Schmidt ◽  
Anja Landgraf ◽  
Martin Schade ◽  
Annett Gawlik ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Irradiation ◽  
Excimer Laser ◽  
Polycrystalline Silicon ◽  
Solid Phase ◽  
Solid Phase Epitaxy ◽  
Silicon Thin Films ◽  
Excimer Laser Irradiation

Ion Beam Study of Early Stages of Growth of GaN films on Sapphire

2002 ◽  
Vol 743 ◽  
Author(s):  
Eugen M. Trifan ◽  
David C. Ingram
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ion Beam ◽  
Ex Situ ◽  
Crystallographic Axis ◽  
In Situ Characterization ◽  
X Ray ◽  
Ion Channeling ◽  
Stages Of Growth ◽  
Early Stages

ABSTRACTAn innovative approach for in-situ characterization has been used in this work to investigate the composition, growth mode, morphology and crystalline ordering of the early stages of growth of GaN films grown on sapphire by MOCVD for substrate temperatures in the range of 450°C to 1050°C. We have performed in-situ characterization by Rutherford Backscattering Spectroscopy (RBS), Ion Channeling, X-ray Photoelectron Spectroscopy (XPS), and Low Energy Electron Diffraction. Ex-situ the films have been characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and thickness profilometry. The films have been grown in an in-house designed and build MOCVD reactor that is attached by UHV lines to the analysis facilities. RBS analysis indicated that the films have the correct stoichiometry, have variable thickness and for low substrate temperature completely cover the substrate while for temperatures 850°C and higher islands are formed that may cover as few as 5 percent of the substrate. From Ion Channeling and LEED we have determined the crystallographic phase to be wurtzite. The crystalline quality increases with higher deposition temperature and with thickness. The films are epitaxialy grown with the <0001> crystallographic axis and planes of the GaN films aligned with the sapphire within 0.2 degrees.

scholarly journals In situ spectroscopic monitoring of CO2 reduction at copper oxide electrode

2017 ◽  
Vol 197 ◽  
pp. 517-532 ◽  
Author(s):  
Liying Wang ◽  
Kalyani Gupta ◽  
Josephine B. M. Goodall ◽  
Jawwad A. Darr ◽  
Katherine B. Holt
Keyword(s):  
Infrared Spectroscopy ◽  
Copper Oxide ◽  
Photoelectron Spectroscopy ◽  
Co2 Reduction ◽  
Modified Electrodes ◽  
Starting Material ◽  
Ex Situ ◽  
Spectroscopic Monitoring ◽  
Carbonate Species

Copper oxide modified electrodes were investigated as a function of applied electrode potential using in situ infrared spectroscopy and ex situ Raman and X-ray photoelectron spectroscopy. In deoxygenated KHCO3 electrolyte bicarbonate and carbonate species were found to adsorb to the electrode during reduction and the CuO was reduced to Cu(i) or Cu(0) species. Carbonate was incorporated into the structure and the CuO starting material was not regenerated on cycling to positive potentials. In contrast, in CO2 saturated KHCO3 solution, surface adsorption of bicarbonate and carbonate was not observed and adsorption of a carbonato-species was observed with in situ infrared spectroscopy. This species is believed to be activated, bent CO2. On cycling to negative potentials, larger reduction currents were observed in the presence of CO2; however, less of the charge could be attributed to the reduction of CuO. In the presence of CO2 CuO underwent reduction to Cu2O and potentially Cu, with no incorporation of carbonate. Under these conditions the CuO starting material could be regenerated by cycling to positive potentials.

Production of Electronically Excited P2 and in from ArF Excimer Laser Irradiation of InP

1986 ◽  
Vol 75 ◽  
Author(s):  
V. M. Donnelly ◽  
V. R. McCrary ◽  
D. Brasen
Keyword(s):  
Excimer Laser ◽  
Laser Frequency ◽  
Laser Exposure ◽  
Resonance Fluorescence ◽  
Thermally Activated ◽  
Ejection Process ◽  
Electronically Excited ◽  
Excimer Laser Irradiation ◽  
Arf Excimer Laser ◽  
193 Nm

AbstractWe have investigated the decomposition of single-crystal InP surfaces irradiated by a 193 nm ArF excimer laser. These studies provide insight into mechanisms of thermal decomposition, surface diffusion and epitaxy. Pulsed laser exposure leads to evolution of P2 from the surface which is detected by resonance fluorescence resulting from a fortuitous overlap of the v″ = 0 with the laser frequency. P2-evolution occurs above a threshold fluence of 0.12 J/cm2 and lags the peak laser intensity by ∼20 nsec. These observations are explained by a thermally activated decomposition mechanism, as opposed to any direct, photochemical ejection process. Peak surface temperatures have been calculated and are used to predict P2 yields as a function of fluence and time which are in good agreement with experiments. These findings are also discussed in relation to previous studies of excimer laser stimulated growth of InP.

Structural and Morphological Properties of Ultrathin HfO2 Dielectrics on 4H-SiC (0001)

2006 ◽  
Vol 527-529 ◽  
pp. 1075-1078 ◽  
Author(s):  
Carey M. Tanner ◽  
Jun Lu ◽  
Hans Olof Blom ◽  
Jane P. Chang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Field Effect Transistors ◽  
High Energy ◽  
Oxide Semiconductor ◽  
Ex Situ ◽  
Morphological Properties ◽  
Layer By Layer ◽  
Island Growth ◽  
X Ray

The material properties of HfO2 thin films were studied to evaluate their potential as a high-κ gate dielectric in 4H-SiC power metal-oxide-semiconductor field effect transistors. Stoichiometric HfO2 films were deposited on n-type 4H-SiC (0001) by atomic layer deposition (ALD) at substrate temperatures of 250-450°C. No significant interfacial layer formation was observed by in-situ X-ray photoelectron spectroscopy (XPS) and an abrupt interface was confirmed by high-resolution transmission electron microscopy (HRTEM). A temperature-dependent transition from amorphous layer-by-layer growth to crystalline three-dimensional island growth was identified by in-situ reflection high-energy electron diffraction (RHEED) and ex-situ atomic force microscopy (AFM). X-ray diffraction (XRD) confirmed the presence of monoclinic HfO2 domains in crystallized films.

In-situ observation of rapid crystalline growth induced by excimer laser irradiation to Ge/Si stacked structure

2006 ◽  
Vol 508 (1-2) ◽  
pp. 53-56
Author(s):  
A. Yamashita ◽  
Y. Okamoto ◽  
S. Higashi ◽  
S. Miyazaki ◽  
H. Watakabe ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Excimer Laser ◽  
In Situ Observation ◽  
Excimer Laser Irradiation ◽  
Crystalline Growth

Laser Irradiation of Ge(100): An Assessment of Surface Order with He Diffraction

1984 ◽  
Vol 35 ◽  
Author(s):  
W. R. Lambert ◽  
P. L. Trevor ◽  
M. T. Schulberg ◽  
M. J. Cardillo ◽  
J. C. Tully
Keyword(s):  
Laser Irradiation ◽  
Excimer Laser ◽  
Low Temperatures ◽  
Thermal Response ◽  
Surface Damage ◽  
Experimental Results ◽  
Excimer Laser Irradiation ◽  
Effects Of Irradiation On ◽  
He Atom

ABSTRACTWe investigate the effects of Nd:YAG and excimer laser irradiation on the Ge(100) surface under UHV conditions over a temperature range 140 < T(K) < 300 using the surface sensitive probe of He atom diffraction. We study the effects of irradiation on surface damage and order using the apparent (2×1) ࢐ c(2×4) transition. We monitor surface contamination in situ. The temporal thermal response is modeled theoretically to aid in assessing the experimental results. The capability to maintain a Ge(100) surface at low temperatures free of contamination and well ordered is demonstrated.

scholarly journals Small AgNP in the Biopolymer Nanocomposite System

2020 ◽  
Vol 21 (24) ◽  
pp. 9388
Author(s):  
Małgorzata Zienkiewicz-Strzałka ◽  
Anna Deryło-Marczewska
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Metallic Nanoparticles ◽  
Silver Ions ◽  
Membrane System ◽  
Added Value ◽  
Ex Situ ◽  
Membrane Properties ◽  
Homogeneous Distribution

In this work, ultra-small and stable silver nanoparticles (AgNP) on chitosan biopolymer (BP/AgP) were prepared by in situ reduction of the diamminesilver(I) complex ([Ag(NH3)2]+) to create a biostatic membrane system. The small AgNP (3 nm) as a stable source of silver ions, their crystal form, and homogeneous distribution in the whole solid membrane were confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The X-ray photoelectron spectroscopy (XPS) and Auger analysis were applied to investigate the elemental composition, concentration, and chemical state of surface atoms. It was found that ultra-small metallic nanoparticles might form a steady source of silver ions and enhance the biostatic properties of solid membranes. Ultra-small AgNP with disturbed electronic structure and plasmonic properties may generate interaction between amine groups of the biopolymer for improving the homogeneity of the nanometallic layer. In this work, the significant differences between the typical way (deposition of ex-situ-prepared AgNP) and the proposed in-situ synthesis approach were determined. The improved thermal stability (by thermogravimetry and differential scanning calorimetry (TG/DSC) analysis) for BP/AgP was observed and explained by the presence of the protective layer of a low-molecular silver phase. Finally, the antibacterial activity of the BP/AgP nanocomposite was tested using selected bacteria biofilms. The grafted membrane showed clear inhibition properties by destruction and multiple damages of bacteria cells. The possible mechanisms of biocidal activity were discussed, and the investigation of the AgNP influence on the bacteria body was illustrated by AFM measurements. The results obtained concluded that the biopolymer membrane properties were significantly improved by the integration with ultra-small Ag nanoparticles, which added value to its applications as a biostatic membrane system for filtration and separation issues.

Characterization of Polyimide Thin Films on Metals

1992 ◽  
Vol 264 ◽  
Author(s):  
Jiong-Ping Lu ◽  
Pradnya V. Nagarkar ◽  
David Volfson ◽  
Klavs F. Jensen ◽  
Stephen D. Senturia
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Ex Situ ◽  
Interfacial Region ◽  
Infrared Reflection Absorption Spectroscopy ◽  
Infrared Reflection ◽  
Polymer Curing ◽  
Tetracarboxylic Dianhydride

AbstractWe describe an approach using thin films on metals as models to study interfacial interactions. Thin films of biphenyl-tetracarboxylic dianhydride (BPDA) - p-phenylene diamine (PPD) based polyimide on Cr and Au surfaces have been investigated using infrared reflection absorption spectroscopy (IRRAS) and x-ray photoelectron spectroscopy (XPS). IRRAS was used for in-situ monitoring of polymer curing processes. Cured polyimide thin films on metals were characterized ex-situ by both XPS and IRRAS. Anhydride was observed to be an intermediate during chemical transformation of polyamic acid to polyimide. Imidization processes were found to be completed after curing at 250°C for thin films. Strong chemical modification of polyimide thin films resulting from interaction with Cr substrates were observed by infrared spectroscopy. These observations were consistent with angle-resolved XPS data showing a different C 1s emission spectrum of polyimide-Cr interfacial region, compared to the polyimide spectrum.

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