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2002

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Articles 3121 - 3150 of 3435

Full-Text Articles in Physical Sciences and Mathematics

Overpressuring, Diagenesis, And Fluid Flow At The Matagorda Island 519 Field, Offshore Texas, Gulf Of Mexico, Kera Gautreau Spears Jan 2002

Overpressuring, Diagenesis, And Fluid Flow At The Matagorda Island 519 Field, Offshore Texas, Gulf Of Mexico, Kera Gautreau Spears

LSU Master's Theses

The relations between overpressuring, diagenesis, and fluid flow in sedimentary basins are complex and multifaceted. The Matagorda Island 519 field (MI 519), offshore Texas, provides an excellent area for investigating some of these relations. The top of overpressure at MI 519 occurs at a depth of 3.5 to 3.8 km in a Lower Miocene deltaic sequence. On the basis of log-derived lithostratigraphy, the pressure seal does not appear to be lithologic in origin. Geochemical, mineralogical, and cuttings information indicate instead that the precipitation of diagenetic calcite and possibly quartz cements has been the major factor in seal development. Stratigraphic variation …

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Distributary Mouth Bar Formation And Channel Bifurcation In The Wax Lake Delta, Atchafalaya Bay, Louisiana, Anton J. Dumars Jan 2002

Distributary Mouth Bar Formation And Channel Bifurcation In The Wax Lake Delta, Atchafalaya Bay, Louisiana, Anton J. Dumars

LSU Master's Theses

The Mississippi River has undergone at least seven cyclic avulsions during the Holocene epoch. The latest avulsion, down the Atchafalaya River into the Gulf of Mexico, has produced two bayhead deltas prograding into Atchafalaya Bay. The Wax Lake Delta, typical of other Mississippi sub-deltas, has a natural anastomosing channel pattern. In contrast, the Atchafalaya Delta, situated in the eastern side of the Bay, has experienced sporadic and limited growth due to the dredging of a navigation channel below natural depth. Channel bifurcation, and sediment transport processes and responses, were investigated in the Wax Lake Delta, using channel flow velocities, suspended …

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Multipole Expansions Of Irreducible Tensor Sets And Some Applications, N. L. Manakov, A. V. Meremianin, Anthony F. Starace Jan 2002

Multipole Expansions Of Irreducible Tensor Sets And Some Applications, N. L. Manakov, A. V. Meremianin, Anthony F. Starace

Anthony F. Starace Publications

A formal multipole expansion of tensor functions dependent on several vector parameters is obtained in an invariant differential form. We apply this result to derive multipole expansions of finite rotation matrices in terms of finite sums of bipolar harmonics. The multipole expansion in terms of bipolar harmonics of unit vectors r1 and r2 are analyzed for functions of the type f (r)Ylm( r) (with r = r1 − r2), which are important in two-center problems. As another example of the application of the multipole expansion technique, reduction formulae are obtained for tensor constructions …

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Estimation Of Standardized Mortality Ratio In Epidemiological Studies, Bingxia Wang Jan 2002

Estimation Of Standardized Mortality Ratio In Epidemiological Studies, Bingxia Wang

Electronic Theses and Dissertations

In epidemiological studies, we are often interested in comparing the mortality rate of a certain cohort to that of a standard population. A standard computational statistic in this regard is the Standardized Mortality Ratio (SMR) @reslow and Day, 1987), given by where 0 is the number of deaths observed in the study cohort from a specified cause, E is the expected number calculated from that population. In occupational epidemiology, the SMR is the most common measure of risk. It is a comparative statistic. It is frequently based on a comparison of the number0 in the cohort with the expected value …

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Virginia Game Fish Tagging Program Annual Report 2001, John A. Lucy, C.M. Bain Iii Jan 2002

Virginia Game Fish Tagging Program Annual Report 2001, John A. Lucy, C.M. Bain Iii

Reports

The Virginia Game Fish Tagging Program (VGFTP), in its seventh year during 2001, systematically trains and assists anglers in tagging a select number of species important to Virginia's marine recreational fishery and maintains the resulting tagging database. A cooperative project of the Virginia Marine Resources Commission and the Virginia Institute of Marine Science (VIMS), the program is primarily funded with revenues from Virginia's saltwater recreational fishing license funds (Recreational Fishing Development Fund). In addition, support for the program is provided by Virginia's Sea Grant Marine Advisory Program at VIMS.

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The Single Row Routing Problem Revisited: A Solution Based On Genetic Algorithms, Albert Y. Zomaya, Roger Karpin, Stephan Olariu Jan 2002

The Single Row Routing Problem Revisited: A Solution Based On Genetic Algorithms, Albert Y. Zomaya, Roger Karpin, Stephan Olariu

Computer Science Faculty Publications

With the advent of VLSI technology, circuits with more than one million transistors have been integrated onto a single chip. As the complexity of ICs grows, the time and money spent on designing the circuits become more important. A large, often dominant, part of the cost and time required to design an IC is consumed in the routing operation. The routing of carriers, such as in IC chips and printed circuit boards, is a classical problem in Computer Aided Design. With the complexity inherent in VLSI circuits, high performance routers are necessary. In this paper, a crucial step in the …

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Call Parameters And Facial Features In Bats: A Surprising Failure Of Form Following Function, Amanda Goudy-Trainor, Patricia W. Freeman Jan 2002

Call Parameters And Facial Features In Bats: A Surprising Failure Of Form Following Function, Amanda Goudy-Trainor, Patricia W. Freeman

School of Natural Resources: Faculty Publications

We attempted to correlate echolocation call parameters to a comprehensive array of ear and nose measurements from 12 families of bats. Surprisingly, we failed to find any significant relationships. We did find consistent differences between nasal and oral emitters such as: (a) nasal emitters have higher frequencies with maximum energy for their size than oral emitters, (b) nasal emitting bats tend to have longer, narrower skulls, and (c) nasal emitters have a shorter distance from the nostril to the eye (muzzle length).

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Effect Of Rf Power On The Electrical Properties Of Glow-Discharge A-Si:H, Hüseyi̇n Tolunay Jan 2002

Effect Of Rf Power On The Electrical Properties Of Glow-Discharge A-Si:H, Hüseyi̇n Tolunay

Turkish Journal of Physics

Hydrogenated amorphous silicon films were prepared in an rf glow-discharge system by decomposing undiluted silane at various rf power densities. Dark conductivity and photoconductivity of the films have been measured in the temperature range 420K-100K at four different photon fluxes. It was observed that both dark conductivity and photoconductivity increase with increasing rf power density.

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Near Bandedge Optical Absorption Processes In Semi Insulating And N-Type Gaas, Tacetti̇n Yildirim, Sebahatti̇n Tüzemen, Seydi̇ Doğan, Beki̇r Gürbulak, Aytunç Ateş, Muhammet Yildirim Jan 2002

Near Bandedge Optical Absorption Processes In Semi Insulating And N-Type Gaas, Tacetti̇n Yildirim, Sebahatti̇n Tüzemen, Seydi̇ Doğan, Beki̇r Gürbulak, Aytunç Ateş, Muhammet Yildirim

Turkish Journal of Physics

Near bandedge optical absorption processes in semi-insulating (SI) GaAs and Te-doped n-type GaAs crystals were investigated in the temperature range 10--300 K. We observed absorption peaks whose maximum energies E_{m}, ranging from 1.498 to 1.485 eV decrease as the temperature increases from 10 K to 100 K. The peaks for both SI and n-type GaAs disappeared above 100 K. Extrapolating the graphs of E$_{g}-E_{m} versus temperature, we observed that near bandedge absorption is overlapped by the conduction band at about 220 K and 260 K for n-type and SI samples, respectively. Furthermore, we demonstrated that the absorption in the region …

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Experimental Investigation Of Temperature Effect On Refractive Index Of Dye Laser Liquids, Şeref Yaltkaya, Ramazan Aydin Jan 2002

Experimental Investigation Of Temperature Effect On Refractive Index Of Dye Laser Liquids, Şeref Yaltkaya, Ramazan Aydin

Turkish Journal of Physics

In this work, refractive index of selected dye laser solutions were measured by fiber optic sensor. The fiber optic probe was dipped into the liquids and according to Fresnel's Reflection Law, refractive index values were obtained at the wavelength of the laser utilized. The solutions consisted of Rhodamine 6G, Rhodamine B and Coumarin 481 dissolved in methanol, and ethylene glycol, respectively. Refractive index variations of the dye solutions and their solvents with temperature were measured and the refractive index temperature coefficient dn/dT were calculated at the wavelength of 780 nm.

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The Contributions Of Anomalous Magnetic Moment To Relativistic Landau Orbits, Ali̇ Havare, Nuri̇ Ünal Jan 2002

The Contributions Of Anomalous Magnetic Moment To Relativistic Landau Orbits, Ali̇ Havare, Nuri̇ Ünal

Turkish Journal of Physics

In this work, the contributions of anomalous magnetic moment to relativistic Landau orbits are calculated by the method of self-field quantum electrodynamics. In addition to contributions from positive energy states new terms from negative energy states that have not been taken into account before are now also included. Contributions from these terms are found to be in the same order as positive terms.

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The Determination Of Thermal Annealing Effect On A-Si:H Films Coated On Glass And On Single Crystalline Of Silicon, Necmi̇ Seri̇n, Tülay Seri̇n, Ali̇ Riza Özdemi̇r, Bora Alkan, Çeli̇k Tarimci, Basri̇ Ünal Jan 2002

The Determination Of Thermal Annealing Effect On A-Si:H Films Coated On Glass And On Single Crystalline Of Silicon, Necmi̇ Seri̇n, Tülay Seri̇n, Ali̇ Riza Özdemi̇r, Bora Alkan, Çeli̇k Tarimci, Basri̇ Ünal

Turkish Journal of Physics

The aim of this study was to examine the effect of thermal annealing on hydrogenated intrinsic amorphous silicon a-Si:H films. Hydrogenated intrinsic amorphous films were seperately coated on glass and single cyrstalline silicon substrates by means of d.c. magnetron sputtering technique. a-Si:H/glass and a-Si:H/c-Si samples were annealed in the temperature range of 23-250^oC, 23-200^oC and 600-1050^oC, respectively. The effect of annealing on the a-Si:H films were examined by means of Infrared vibrational transmittance spectrum technique (IR) in the wavenumber range 4000-400 cm^{-1} and Scanning Electron Microsope (SEM). The results were interpreted in terms of hydrogen diffusion.

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A Method For Identifying Gluon Jets With High Purity In 3-Jet Hadronic Z Decays, Ayda Beddall Jan 2002

A Method For Identifying Gluon Jets With High Purity In 3-Jet Hadronic Z Decays, Ayda Beddall

Turkish Journal of Physics

A method for identifying gluon jets with very high purity is presented and the performance evaluated. Quark and gluon jets from Monte Carlo simulated Hadronic Z decays are identified by energy ordered jets and applying heavy flavour tagging. It is shown that quark and gluon jets can be identified with a purity of about 98%.

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Dependence Of Neutron-Proton Entity Transfer On Superfluid Parameters, Hüseyi̇n Ayteki̇n Jan 2002

Dependence Of Neutron-Proton Entity Transfer On Superfluid Parameters, Hüseyi̇n Ayteki̇n

Turkish Journal of Physics

In this study the nuclear matrix elements of neutron-proton (n-p) entity transfer of even-even nuclei are investigated in the Tamm-Dancoff Approximation (TDA). These matrix elements are used for n-p entity stripping from even-even nuclei and n-p entity absorbing of even-even nuclei. It is shown that the matrix element of 0^{+} \to 0^{+} transition between {\left {Z,N} \right\rangle} and {\left {Z - 2,N - 2} \right\rangle} even-even nuclei via the 1^{+} states of {\left {Z - 1,N - 1} \right\rangle} intermediate nuclei depends only on the superfluid parameters.

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The Investigation Of The E2/M1 Multipole Mixing Ratios And Deformation Parameters Of Electromagnetic Transitions In Decay Of ^{156}Gd, Mehmet Baylan, İhsan Uluer Jan 2002

The Investigation Of The E2/M1 Multipole Mixing Ratios And Deformation Parameters Of Electromagnetic Transitions In Decay Of ^{156}Gd, Mehmet Baylan, İhsan Uluer

Turkish Journal of Physics

The extended Rotation -- Vibration Model (RTV) containing different deformations for protons and neutrons is applied to ^{156}Gd nucleus. Using the Rotation-Vibration Model approach multipole mixing ratios \delta (E2/M1), deformation parameter \beta_{o} , g_{R} factors, and quadrupole moments q_{2} + and q_{o} were calculated.

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Relations For Different Resonators Of Nd:Glass And Nd:Yag Lasers, Erol Taşal, M. Selami̇ Kiliçkaya Jan 2002

Relations For Different Resonators Of Nd:Glass And Nd:Yag Lasers, Erol Taşal, M. Selami̇ Kiliçkaya

Turkish Journal of Physics

Simple relations in terms of effective g parameters are given for linear resonators that contain laser rods with curved endfaces and for symmetrical and asymmetric ring resonators of Nd:Glass and Nd:YAG lasers. The equivalence relationships of thick and thin lenses have been applied.

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Urbach's Rule And Optical Properties For Tlgas_{2}, Aytunç Ateş, Beki̇r Gürbulak, Muhammet Yildirim, Seydi̇ Doğan, Songül Duman, Tacetti̇n Yildirim, Sebahatti̇n Tüzemen Jan 2002

Urbach's Rule And Optical Properties For Tlgas_{2}, Aytunç Ateş, Beki̇r Gürbulak, Muhammet Yildirim, Seydi̇ Doğan, Songül Duman, Tacetti̇n Yildirim, Sebahatti̇n Tüzemen

Turkish Journal of Physics

Absorption measurements were carried out on TlGaS_{2} sample in the temperature range between 10 and 320 K in 10 K steps. There is an abrupt change in the Urbach energy at 180 K and 280 K and steepness parameter at 120 K and 220 K .Obtained from the changing of the Urbach energy, these may be phase transition temperatures. The phonon energies calculated for TlGaS_{2} is 19.7 \pm 5 meV.

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On Numerical Simulations Of Composite Dielectrics In Thermally Stimulated Conditions, Eni̇s Tuncer, Stanislaw M. Gubanski Jan 2002

On Numerical Simulations Of Composite Dielectrics In Thermally Stimulated Conditions, Eni̇s Tuncer, Stanislaw M. Gubanski

Turkish Journal of Physics

A binary composite system with particulated inclusions was considered. First, thermally stimulated depolarization ({\sc tsd}) currents of the system were simulated by altering different parameters of the {\sc tsd} current equation, {\em i.e.}, intrinsic dielectric properties of constituents, conductivity of inclusions, heating rate and activation energy of inclusion conductivity and shape of inclusions. Two different methods of finding the activation energy of {\sc tsd} processes from the simulated {\sc tsd} currents were discussed. Second, we have included the Monte Carlo technique by assuming that the shape factor of inclusions were distributed. These simulations have shown that if the inclusions were …

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Spin Polarized Cold And Hot Dense Neutron Matter, S. A. Moharrm, Azza O. El-Shal Jan 2002

Spin Polarized Cold And Hot Dense Neutron Matter, S. A. Moharrm, Azza O. El-Shal

Turkish Journal of Physics

The Thomas-Fermi (TF) model is used to calculate the equation of state of thermal polarized neutron matter. The properties of cold and hot neutron matter have been investigated. A realistic density-dependent M3Y effective nucleon-nucleon (NN) interaction where the Yukawa strengthes are based on the G-matrix of the Paris interaction has been used. Special attention is devoted to the effect of the spin excess parameter on these properties. Moreover, the effect of some realistic density dependence has been studied. The results obtained are in reasonable agreement with previous theoretical estimates using different methods of calculation.

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Radiation Transfer For Exponential C(X), Fatma Erdoğan Jan 2002

Radiation Transfer For Exponential C(X), Fatma Erdoğan

Turkish Journal of Physics

The emergent flux for radiation transfer in inhomogeneous half-space for exponential c(x) = 1 + ke^{-mx}/1 + be^{-mx} is obtained by using Modified-Eddington method, where m, b, k are constants. As a result of this work, angular flux is obtained in terms of Jacobi polynomials.

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Structural Analysis Of A Gaas/Al_Xga_{1-X} As Hot Electron Light Emitter Using Double Axis X-Ray Diffraction, Ali̇ Teke Jan 2002

Structural Analysis Of A Gaas/Al_Xga_{1-X} As Hot Electron Light Emitter Using Double Axis X-Ray Diffraction, Ali̇ Teke

Turkish Journal of Physics

We report on interference peaks in double axis x-ray rocking curves of tunable wavelength hot electron light emitters. The device is based on a p-GaAs and n-Ga_{1-x}Al_xAs heterojunction containing an inversion layer on the p- side, and GaAs quantum wells on the n- side of the junction, a construction known as HELLISH-2 (Hot Electron Light Emitting and Lasing in Semiconductor Heterostructure-Type 2). The interference has been shown to strongly depend on the periodicy of the device structure. Experimental curves are compared with simulated rocking curves. Some structural parameters, such as total epilayer thickness, composition ratio and quantum well width and …

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On The Numerical Solution And Limitations Of Energy Equation For Vertical Bridgman System With Varying Temperature Gradient At The Boundary, Ergün Taşarkuyu, Evren Akar, Bülent Gülteki̇n Akinoğlu Jan 2002

On The Numerical Solution And Limitations Of Energy Equation For Vertical Bridgman System With Varying Temperature Gradient At The Boundary, Ergün Taşarkuyu, Evren Akar, Bülent Gülteki̇n Akinoğlu

Turkish Journal of Physics

In vertical Bridgman crystal growth systems solid-liquid interface shape is one of the most important factors affecting the product quality. Most of the theoretical studies to determine the interface shape consider the numerical solution to the heat-conduction and the energy equation. The purpose of this work is to present and discuss a numerical solution to the energy equation (also called the convection-diffusion equation) for a vertical Bridgman system with varying temperature gradient at the boundary. Different system parameters are examined and the importance of the pulling rate for different materials in the utilization of the energy equation is emphasized. The …

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The Electron-Photon Coincidence Method And Its Application To Excitation Of The 2p State Of Atomic Hydrogen, Hüseyi̇n Ali̇ Yalim, Albert Crowe Jan 2002

The Electron-Photon Coincidence Method And Its Application To Excitation Of The 2p State Of Atomic Hydrogen, Hüseyi̇n Ali̇ Yalim, Albert Crowe

Turkish Journal of Physics

Early measurements of atomic excitation by electron scattering observed either the scattered electron or decay photon. An excited state can not be completely defined by such experiments due to loss of information. Therefore a new method was developed in the early 70's called the correlation method. The new correlation method involves the detection of both the scattered electron and photon arising from the same collision using coincidence techniques. This method enables a full description of an excited state. In this paper, we give a discussion of to the method and its application to excitation of the 2p state of atomic …

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A Quadratic Boundary Element Formulation For Neutron Diffusion Equation, Bi̇lge Özgener, Havar Isikli Jan 2002

A Quadratic Boundary Element Formulation For Neutron Diffusion Equation, Bi̇lge Özgener, Havar Isikli

Turkish Journal of Physics

The boundary element method (BEM) is a technique based on the principle of the conversion of the governing differential equation to the boundary integral equation with consequent reduction by one in the dimension of the problem. In this work, quadratic boundary elements and thus BEM have been applied to neutron diffusion calculations to render the treatment of curved boundaries possible. The results of the developed computer program BENDQ has been compared to the analytical solutions and validated.

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Contribution To The Relationship Between Solar Radiation And Sunshine Duration In The Tropics: A Case Study Of Experimental Data At Ilorin, Nigeria, Sunday O. Udo Jan 2002

Contribution To The Relationship Between Solar Radiation And Sunshine Duration In The Tropics: A Case Study Of Experimental Data At Ilorin, Nigeria, Sunday O. Udo

Turkish Journal of Physics

From monthly average daily values of clearness index and relative sunshine spanning a period of two years, two equations (linear and quadratic) of the Angstrom-Prescott model have been developed for the estimation of global solar irradiation at Ilorin (Lat. 8°32'N, Long. 4°34'E), a tropical location. Comparison of the regression coefficients of the linear type model showed that the values are quite consistent with those quoted in the literature for the Tropics. The predictive efficiencies of these two models are also compared with those which are believed to be applicable globally, and those developed for the Nigerian environment. Although some of …

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Short-Range Correlations In Coupled Quantum-Wire Systems, A. Yurtsever, B. Tanatar Jan 2002

Short-Range Correlations In Coupled Quantum-Wire Systems, A. Yurtsever, B. Tanatar

Turkish Journal of Physics

We study the contact values of the inter-wire pair-correlation function in electron-electron and electron-hole double-wire systems. For this purpose the ladder approximation as generalized to multicomponent systems is used. The ladder approximation yields positive values for the inter-wire g_{ee}(0) and g_{eh}(0) for all values of the density parameter r_s and distance d between the wires. This allows us to infer possible instabilities in the system more reliably compared to other approaches. We also investigate the effects of quantum-wire width and screening on the inter-wire pair-correlation functions. PACS numbers: 05.30.Fk, 73.20.Dx, 71.45.Gm, 73.40.Kp

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Excess Properties Of Alcohol - Water Systems At 298.15 K, Hülya Yilmaz Jan 2002

Excess Properties Of Alcohol - Water Systems At 298.15 K, Hülya Yilmaz

Turkish Journal of Physics

Dielectric constants \varepsilon, viscosities \eta, refractive indices n and densities d have been measured over the entire mole fraction range for the water - methyl, ethyl, n-propyl alcohol binary systems at 298.15 K. From the experimental data excess dielectric constants \varepsilon^E, excess viscosities \eta^E and Kirkwood correlation factors g_k have been calculated and studied. Their behaviour suggests the existence of intermolecular interactions and plotted curves show that excess dielectric constant and g_k values decrease with the increasing of carbon atom number, while excess viscosity increases.

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Effects Of Substrate Temperature On Properties Of A-Sin_X:H Films, Tayyar Güngör, Hüseyi̇n Tolunay Jan 2002

Effects Of Substrate Temperature On Properties Of A-Sin_X:H Films, Tayyar Güngör, Hüseyi̇n Tolunay

Turkish Journal of Physics

Hydrogenated amorphous silicon nitride films were prepared in an rf glow-discharge system by the decomposition of silane + nitrogen gas mixture at various substrate temperatures. The effects of substrate temperature on the electrical and optical properties of the films have been studied.

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Determination Of The Trapping Parameters Of Zns Thin Films Developed By Chemical Spraying Technique, A. Necmetti̇n Yazici, Mustafa Öztaş, Meti̇n Bedi̇r, Refi̇k Kayali Jan 2002

Determination Of The Trapping Parameters Of Zns Thin Films Developed By Chemical Spraying Technique, A. Necmetti̇n Yazici, Mustafa Öztaş, Meti̇n Bedi̇r, Refi̇k Kayali

Turkish Journal of Physics

In this study, the thermoluminescence (TL) glow curves of ZnS thin films developed using chemical spraying technique were carefully investigated and its kinetic parameters were determined with a specially developed computer program. The results of investigations have shown that the trapping states of ZnS thin films could not be analysed by a well-known Randall-Wilkins (RW) or General-Order (GO) models. A detailed investigation of experimental results has indicated that the trapping states have a form that is best described by a distribution of energies. After the comparison of the experimental glow curves of ZnS thin films with theoretically generated glow curves, …

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Monte Carlo Simulation Of Electron Transport In Insb, Ö. Özbaş, M. Akarsu Jan 2002

Monte Carlo Simulation Of Electron Transport In Insb, Ö. Özbaş, M. Akarsu

Turkish Journal of Physics

Transport properties of indium antimonide in an electric field have been calculated at 77 K. The calculation shows that ionized impurity scattering plays a dominant role in InSb at low electric field. The mobility, mean energy, and drift velocity are calculated as a function of the electric field strength, and comparison is made with previous theoretical results. Types of the scattering mechanisms and percentage of each mechanism in the total scattering events are determined.

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