Formation Mechanism and Recombination-Enhanced Dissociation of a Hydrogen-Carbon Complex in Silicon

1992 ◽  
Vol 262 ◽  
Author(s):  
Yoichi Kamiura ◽  
Fumio Hashimoto ◽  
Minoru Yoneta
Keyword(s):  
Formation Mechanism ◽  
Chemical Etching ◽  
Surface Region ◽  
Electronic Energy ◽  
Hydrogen Atoms ◽  
Electron Hole ◽  
Near Surface ◽  
Depth Profiles ◽  
Schottky Structure ◽  
Hole Recombination

ABSTRACTWc have found that chemical etching induced an electron trap E3 (0.15) into n-typc Si. We attribute this trap to a hydrogen-carbon complex on the basis of available experimental data. By measuring DLTS depth profiles of the E3 trap, we propose a model of the formation mechanism of the hydrogen-carbon complex as follows. Hydrogen atoms arc adsorbed on the Si surface to terminate Si dangling bonds during chemical etching, and after the etching some unstably adsorbed ones diffuse into the near-surface region of silicon and are trapped by carbon to form the complex. The E3 trap is stable up to 100δC in the dark but is annihilated by the illumination of band gap light around 250K only outside the depletion layer of the Schottky structure. This provides unambiguous experimental evidence for the recombination-enhanced dissociation, in which the electronic energy released by the electron-hole recombination at the E3 level is converted into local kinetic energy of hydrogen to be released from carbon.

Near Surface Defect Distribution in Silicon Under Etching

1998 ◽  
Vol 510 ◽  
Author(s):  
Nikolai A. Yarykin
Keyword(s):  
Room Temperature ◽  
Surface Defect ◽  
Diffusion Length ◽  
Characteristic Length ◽  
Hydrogen Atoms ◽  
Near Surface ◽  
Defect Distribution ◽  
Depth Profiles ◽  
Silicon Crystals ◽  
Defect Interaction

AbstractThe distribution of hydrogen penetrated into n-type silicon crystals during chemical etching is described mathematically. The depth profiles of the defects passivated by hydrogen and of defect-hydrogen complexes are also calculated. Comparison with the experimental data obtained on the silicon crystals with radiation defects and doped with transition metals reveals that the model adequately describes the processes in the crystal. By comparing the parameters of the depth profiles, the passivation and appearance of different defects are shown to be caused by the same diffusing species. The number of hydrogen atoms contained in the defect-hydrogen complexes and the distance of the hydrogen-defect interaction are determined from the characteristic length of the defect distribution. The diffusion length (1 to 3 νm) and diffusivity (> 5-10−9 cm2s−1) of hydrogen at room temperature are found indirectly based on the other defect distribution.

Reconstruction-dependent electron-hole recombination on GaAs(001) surfaces studied by using near-surface quantum wells

1996 ◽  
Vol 53 (12) ◽  
pp. 7880-7883 ◽  
Author(s):  
Hiroshi Yamaguchi ◽  
Kiyoshi Kanisawa ◽  
Yoshiji Horikoshi
Keyword(s):  
Quantum Wells ◽  
Electron Hole ◽  
Near Surface ◽  
Hole Recombination

Metal Tungstate Based Nanocomposites for Environmental Applications: Photocatalysis Mini-Review

2020 ◽  
Vol 18 (12) ◽  
pp. 853-860
Author(s):  
Mohamed Jaffer Sadiq Mohamed
Keyword(s):  
Photogenerated Electron ◽  
Surface Region ◽  
Electron Hole ◽  
Light Reaction ◽  
Natural Toxins ◽  
Metal Tungstate ◽  
Treatment Measures ◽  
Reaction Capacity ◽  
Photocatalytic Applications ◽  
Hole Recombination

Photocatalysis is viewed as perhaps the best-progressed treatment measures in eliminating numerous dangerous natural toxins from wastewater. It enjoys numerous benefits, however some downsides are: (i) Fast photogenerated electron–hole recombination productivity, (ii) they restricted noticeable light reaction capacity, (iii) low specific surface region, and (iv) the expense of reagents utilization. To improve the economy of the process, it is likewise needed to expand the catalyst’s effectiveness. Consequently, there is an extraordinary requirement for the improvement of elite catalysts. This mini-review survey addresses the basics and uses of photocatalytic materials on metal tungstate-based nanocomposites. The mini-review shows how metal tungstate-based nanocom-posites can help take care of ecological issues. This mini-review also expected survey gives outlines, synthesis, characterizations, and exploration discoveries in the field of metal tungstate-based nanocomposites for photocatalytic applications in the future examination.

Synthesis of MOS2 Phase in the Near Surface Region of Al2O3 and ZrO2 by Ion Implantation

1989 ◽  
Vol 157 ◽  
Author(s):  
A.K. Rai ◽  
R.S. Bhattacharya ◽  
S.C. Rung ◽  
D. Patrizio
Keyword(s):  
Electron Microscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Surface Region ◽  
Furnace Annealing ◽  
Near Surface ◽  
Depth Profiles ◽  
Annealing Conditions ◽  
Transmission Electron ◽  
Experimental Findings

ABSTRACTAl2O3 and ZrO2 substrates were coimplanted with 175 keV Mo+ and 74 keV S+ at doses of 1×10 cm−2 and 2×1017 cm−2 respectively. The energies of Mo+ and S+ ions were chosen to provide a nearly overlapping depth profiles in both substrates. Rutherford backscattering (RBS), Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) techniques were used for characterization. The as implanted surface of Al2O3 became amorphous while as implanted ZrO2 surface remained crystalline. The MoS2 phase was observed in the as implanted ZrO2. The MoS2 phase was observed in the implanted region of Al2O3 and ZrO2 after furnace annealing at 700°C. Thermodynamic calculations were performed to predict the equilibrium binary phase formed in Al2O3 and ZrO2 under the present implant and annealing conditions. The predictions agree with the experimental findings.

Possible behavior of a diamond (111) surface in methane/hydrogen systems

1990 ◽  
Vol 5 (11) ◽  
pp. 2296-2304 ◽  
Author(s):  
Steven M. Valone ◽  
Mitchell Trkula ◽  
Joseph R. Laia
Keyword(s):  
Gas Phase ◽  
Film Growth ◽  
Surface Region ◽  
Carbon Cluster ◽  
Heat Of Formation ◽  
Hydrogen Atoms ◽  
Near Surface ◽  
Coverage Dependence ◽  
Diamond Film Growth ◽  
Hydrogen Systems

A combined numerical and experimental investigation into the behavior of diamond (111) surfaces in plasma CVD reactors is presented. Numerically, semiempirical molecular orbital methods are used as a model of diamond (111) surfaces represented by a 20-atom carbon cluster plus surface species. The abstraction of hydrogen atoms by gas-phase hydrogen atoms, the coverage dependence of the heat of formation for submonolayers of CH3 and C2H groups coadsorbed with H, and the energy change for abstraction of H atoms from the surface by various radicals in the gas phase are examined. No barrier to abstraction is found, steric effects in achieving clusters of CH3 groups are large, and C2H and atomic oxygen are found to be the most energetically favored for removal of adsorbed H. Experimentally, relative concentrations of atomic H in the near-surface region as a function of added O2 mole fraction were measured. A weak dependence on O2 concentration is observed, but does not appear to be significant enough to account for observed changes in growth rate. This suggests that other radical species be investigated for their contribution to diamond film growth.

Preparation of cross-sectional samples for near-surface TEM studies

1987 ◽  
Vol 45 ◽  
pp. 380-381
Author(s):  
R.C. Dickenson ◽  
K.R. Lawless
Keyword(s):  
Standard Sample ◽  
Surface Region ◽  
Specimen Preparation ◽  
Thick Sheet ◽  
Drill Bit ◽  
Sample Holder ◽  
Metal Interface ◽  
Cross Sectional ◽  
Near Surface ◽  
Cold Worked

In thermal oxidation studies, the structure of the oxide-metal interface and the near-surface region is of great importance. A technique has been developed for constructing cross-sectional samples of oxidized aluminum alloys, which reveal these regions. The specimen preparation procedure is as follows: An ultra-sonic drill is used to cut a 3mm diameter disc from a 1.0mm thick sheet of the material. The disc is mounted on a brass block with low-melting wax, and a 1.0mm hole is drilled in the disc using a #60 drill bit. The drill is positioned so that the edge of the hole is tangent to the center of the disc (Fig. 1) . The disc is removed from the mount and cleaned with acetone to remove any traces of wax. To remove the cold-worked layer from the surface of the hole, the disc is placed in a standard sample holder for a Tenupol electropolisher so that the hole is in the center of the area to be polished.

Preparation of Backthinned Ceramic Specimens

1985 ◽  
Vol 43 ◽  
pp. 182-183
Author(s):  
A. T. Fisher ◽  
P. Angelini
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Vacuum System ◽  
Back Surface ◽  
Surface Microstructure ◽  
Ion Milling ◽  
Near Surface ◽  
Depth Profiles ◽  
Analytical Electron ◽  
Ion Implanted

Analytical electron microscopy (AEM) of the near surface microstructure of ion implanted ceramics can provide much information about these materials. Backthinning of specimens results in relatively large thin areas for analysis of precipitates, voids, dislocations, depth profiles of implanted species and other features. One of the most critical stages in the backthinning process is the ion milling procedure. Material sputtered during ion milling can redeposit on the back surface thereby contaminating the specimen with impurities such as Fe, Cr, Ni, Mo, Si, etc. These impurities may originate from the specimen, specimen platform and clamping plates, vacuum system, and other components. The contamination may take the form of discrete particles or continuous films [Fig. 1] and compromises many of the compositional and microstructural analyses. A method is being developed to protect the implanted surface by coating it with NaCl prior to backthinning. Impurities which deposit on the continuous NaCl film during ion milling are removed by immersing the specimen in water and floating the contaminants from the specimen as the salt dissolves.

The Effects of Ion Implantation on the Surface Features of Inconel 600

1985 ◽  
Vol 43 ◽  
pp. 288-289
Author(s):  
John D. Rubio
Keyword(s):  
Grain Boundary ◽  
Ion Implantation ◽  
Nuclear Power ◽  
Power Plants ◽  
Surface Region ◽  
Selective Dissolution ◽  
Boundary Region ◽  
Near Surface ◽  
Inconel 600 ◽  
Steam Generator Tubing

The degradation of steam generator tubing at nuclear power plants has become an important problem for the electric utilities generating nuclear power. The material used for the tubing, Inconel 600, has been found to be succeptible to intergranular attack (IGA). IGA is the selective dissolution of material along its grain boundaries. The author believes that the sensitivity of Inconel 600 to IGA can be minimized by homogenizing the near-surface region using ion implantation. The collisions between the implanted ions and the atoms in the grain boundary region would displace the atoms and thus effectively smear the grain boundary.To determine the validity of this hypothesis, an Inconel 600 sample was implanted with 100kV N2+ ions to a dose of 1x1016 ions/cm2 and electrolytically etched in a 5% Nital solution at 5V for 20 seconds. The etched sample was then examined using a JEOL JSM25S scanning electron microscope.

Microstructural changes of Aluminum Nitride after laser irradiation and electroless copper deposition

1994 ◽  
Vol 52 ◽  
pp. 636-637
Author(s):  
S. Cao ◽  
A. J. Pedraza ◽  
L. F. Allard
Keyword(s):  
Aluminum Nitride ◽  
Laser Irradiation ◽  
Electroless Deposition ◽  
Thermal Evaporation ◽  
Surface Region ◽  
Near Surface ◽  
Laser Patterning ◽  
Electroless Copper ◽  
Excimer Laser Irradiation ◽  
Laser Effect

Excimer-laser irradiation strongly modifies the near-surface region of aluminum nitride (AIN) substrates. The surface acquires a distinctive metallic appearance and the electrical resistivity of the near-surface region drastically decreases after laser irradiation. These results indicate that Al forms at the surface as a result of the decomposition of the Al (which has been confirmed by XPS). A computer model that incorporates two opposing phenomena, decomposition of the AIN that leaves a metallic Al film on the surface, and thermal evaporation of the Al, demonstrated that saturation of film thickness and, hence, of electrical resistance is reached when the rate of Al evaporation equals the rate of AIN decomposition. In an electroless copper bath, Cu is only deposited in laser-irradiated areas. This laser effect has been designated laser activation for electroless deposition. Laser activation eliminates the need of seeding for nucleating the initial layer of electroless Cu. Thus, AIN metallization can be achieved by laser patterning followed by electroless deposition.

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