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In this work, we carried out in-depth study of the structural, electronic, and optical properties of intrinsic, fluorine (F)- and chlorine (Cl)-doped Sn[O.sub.2], using a pseudo-potential plane-wave scheme in the framework of the density functional theory. We found that the substitution of oxygen by F or Cl elements slightly modified the crystalline parameters without altering the stability of Sn[O.sub.2] compounds. The doping of tin oxide by these two halogens is confirmed by the displacement of the Fermi level position to the conduction band. Consequently, the doped materials are strongly degenerated as illustrated by the Moss-Burstein shift: 2.310 and 2.332 eV for F:Sn[O.sub.2] and Cl:Sn[O.sub.2], respectively. On the other hand, the density of states and Mulliken population analysis show that the covalent character of Sn-O bond is maintained after doping, while Sn-X (X = F or Cl) bond reveals an ionic nature. In terms of optical properties after doping, intrinsic Sn[O.sub.2] exhibits low absorption, while the doped ones are transparent in the visible range, making them more efficient in photovoltaic applications. Moreover, in the ultraviolet (UV) scale, pure and doped tin oxide compounds show better absorption, which may be beneficial for use in devices of protection against UV light and UV absorbers or sensors. Finally, the plasma frequencies of 28.22, 29.16, and 27.67 eV for pure, F-, and Cl-doped Sn[O.sub.2], respectively, were obtained. Keywords: Sn[O.sub.2], doping, fluorine, chlorine, structural properties, electronic properties, optical properties, density functional theory, 1. Introduction Transparent conducting oxides (TCO) are wide band gap semiconductors in the range of 3.01-4.6 eV, which depends on the method used for their deposition [1]. Their transport properties [...]

First principles calculations in the context of density functional theory (DFT) provides a platform to investigate the material's properties in a way to explain the physics of solids. Electronic, structural, and optical properties for pure and Cu-doped LaAl[O.sub.3] are investigated. The study reveals that the band structure of LaAl[O.sub.3] after the inclusion of Cu at the La site is affected significantly. Due to the substitution of Cu, there is a decrease in the band gap from 3.02 eV to 2.95 eV. Furthermore, the partial density of states of LaAl[O.sub.3] changes significantly after Cu doping, which has confirmed the doping effect on intrinsic LaAl[O.sub.3]. The p and d states play a vital role on top of the valence band. The range in which the top of a valence band lies is from 0 eV to -9 eV having a significant effect and it is because of Cu-d states. The optical properties of both pure and doped systems were analyzed. Redshift was observed as absorption edge shifted from 4.5 eV to 4.0 eV and even the refractive index reduces from 2.25 to 1.0, which means the Cu inclusion significantly play its role to tailor optical properties. Hence Cu-doping affects the properties of LaAl[O.sub.3] and makes it a suitable candidate for use in different optical devices. Key words: doping, density functional theory, and gap, density of states, optical properties, refractive index. Des calculs bases sur les principes premiers, dans le cadre de la theorie de la fonctionnelle de densite (TFD/DFT), nous fournissent une plateforme pour examiner les proprietes des materiaux en physique du solide. Nous analysons les proprietes electroniques, structurelles et optiques du LaAl[O.sub.3] pur et dope au Cu. L'etude revele que la structure de bande du LaAl[O.sub.3] est affectee de facon significative apres l'inclusion de Cu sur les sites de La. Suite a cette substitution, la bande interdite (gap) est diminuee de 3.02 eV a 2.95 eV. De plus, la densite partielle d'etats (DPE/PDOS) du LaAl[O.sub.3] change de facon marquee apres le dopage au Cu, ce qui confirme l'effet du dopage sur le LaAl[O.sub.3]. Les etats p et d jouent un role crucial sur le haut de la bande de valence. Le domaine dans lequel se trouve le haut de la bande de valence se situe entre 0 eV et -9 eV, un effet significatif cause par les etats d du Cu. Nous analysons les proprietes optiques des systemes purs et dopes. Un decalage vers le rouge est observe suite au deplacement du seuil d'absorption de 4.5 eV a 4.0 eV et meme l'indice de refraction est reduit de 2.25 a 1.0, ce qui signifie que l'inclusion du Cu joue son role pour ajuster les proprietes optiques. Par consequent, les effets du dopage par le Cu affectent les proprietes du LaAl[O.sub.3] et en font un bon candidat pour utilisation dans les dispositifs optiques. [Traduit par la Redaction] Mots-cles : dopage, theorie de la fonctionnelle de densite, bande interdite, densite d'etats, proprietes optiques, indice de refraction., 1. Introduction The power and energy crises demand that humans establish new ideas and perceptions; therefore different theoretical and experimental methods in research have been developed in the materials field. [...]

Classification is an important task at which both biological and artificial neural networks excel.sup.1,2. In machine learning, nonlinear projection into a high-dimensional feature space can make data linearly separable.sup.3,4, simplifying the classification of complex features. Such nonlinear projections are computationally expensive in conventional computers. A promising approach is to exploit physical materials systems that perform this nonlinear projection intrinsically, because of their high computational density.sup.5, inherent parallelism and energy efficiency.sup.6,7. However, existing approaches either rely on the systems' time dynamics, which requires sequential data processing and therefore hinders parallel computation.sup.5,6,8, or employ large materials systems that are difficult to scale up.sup.7. Here we use a parallel, nanoscale approach inspired by filters in the brain.sup.1 and artificial neural networks.sup.2 to perform nonlinear classification and feature extraction. We exploit the nonlinearity of hopping conduction.sup.9-11 through an electrically tunable network of boron dopant atoms in silicon, reconfiguring the network through artificial evolution to realize different computational functions. We first solve the canonical two-input binary classification problem, realizing all Boolean logic gates.sup.12 up to room temperature, demonstrating nonlinear classification with the nanomaterial system. We then evolve our dopant network to realize feature filters.sup.2 that can perform four-input binary classification on the Modified National Institute of Standards and Technology handwritten digit database. Implementation of our material-based filters substantially improves the classification accuracy over that of a linear classifier directly applied to the original data.sup.13. Our results establish a paradigm of silicon-based electronics for small-footprint and energy-efficient computation.sup.14. The nonlinearity of hopping conduction in a disordered network of boron dopant atoms in silicon is used to perform nonlinear classification and feature extraction., Author(s): Tao Chen [sup.1] , Jeroen van Gelder [sup.1] , Bram van de Ven [sup.1] , Sergey V. Amitonov [sup.1] , Bram de Wilde [sup.1] , Hans-Christian Ruiz Euler [sup.1] [...]

The efficiency with which polymeric semiconductors can be chemically doped--and the charge carrier densities that can thereby be achieved--is determined primarily by the electrochemical redox potential between the [pi]-conjugated polymer and the dopant species.sup.1,2. Thus, matching the electron affinity of one with the ionization potential of the other can allow effective doping.sup.3,4. Here we describe a different process--which we term 'anion exchange'--that might offer improved doping levels. This process is mediated by an ionic liquid solvent and can be pictured as the effective instantaneous exchange of a conventional small p-type dopant anion with a second anion provided by an ionic liquid. The introduction of optimized ionic salt (the ionic liquid solvent) into a conventional binary donor-acceptor system can overcome the redox potential limitations described by Marcus theory.sup.5, and allows an anion-exchange efficiency of nearly 100 per cent. As a result, doping levels of up to almost one charge per monomer unit can be achieved. This demonstration of increased doping levels, increased stability and excellent transport properties shows that anion-exchange doping, which can use an almost infinite selection of ionic salts, could be a powerful tool for the realization of advanced molecular electronics. The limitations of conventional chemical doping of polymeric semiconductors can be overcome by adding a second ionic species into the system, leading to enhanced doping, electrical conductivity and stability., Author(s): Yu Yamashita [sup.1] [sup.2] [sup.3] , Junto Tsurumi [sup.1] [sup.2] [sup.3] , Masahiro Ohno [sup.1] [sup.2] , Ryo Fujimoto [sup.1] [sup.2] , Shohei Kumagai [sup.1] [sup.2] , Tadanori Kurosawa [...]

The polyaniline (PANI) was synthesized using different dopant acids (iminodiacetic, methanesulfonic, phosphoric, and boron trifuoride) using oxidative polymerization method. These obtained new polymers were characterized by using spectrophotometric methods such as FTIR, UV-vis. The calculated value of the optical energy gap for the doped investigated polymer was reached to 3.70 eV for PANI-OH doped by boron trifuoride. The conductivity of the polymers was also investigated. The direct current (dc) conductivity as a function of temperature for the doped polymers has been studied. The results show increase in the conductivity with increase in temperature. Also, the value of dc conductivity at room temperature was found to be greater than that of the undoped PANI by nearly one to four orders of magnitude with respect to the used dopant acid. POLYM. ENG. SCI., 53:251-256, 2013. © 2012 Society of Plastics Engineers, INTRODUCTION With the discovery of intrinsically conducting polymers (ICPs) in 1960 (1), an attractive subject of research was initiated because of the interesting properties and its numerous application possibilities. ICPs [...]

Obtaining higher quantum efficiency and more stable GaAs photocathodes has been an important developmental direction in the investigation of GaAs photocathodes. One significant approach to this problem is to improve the electron diffusion length. We put forward and investigate an exponential doping mode GaAs photocathode. It was proved by theoretical and experimental results that, because the exponential doping structure is in favor of forming a directional constant built-in electric field, the electron diffusion and drift length of the cathode material can accordingly be enhanced. The mathematical expression of the electron diffusion and drift length [L.sub.DE] of an exponential doping photocathode was deduced, and the relationship between the doping coefficient and the electron diffusion and drift length is made certain. This investigation contributes to the understanding of varied doping GaAs photocathodes and provides guidance to optimize the doping structure of GaAs photocathodes for higher quantum efficiency. [c] 2009 Optical Society of America OCIS codes: 160.2100, 250.0250.

We demonstrate an opto-optical gain-clamped L-band erbium-doped fiber amplifier by manipulating the C-band lasing wavelength as the control signal. The L-band gain-clamped value is achieved by tuning the control laser in the C-band wavelength range that propagates in the opposite direction to the L-band signal. Within the wavelength range of 1538 nm and 1560 nm, the L-band gain decreases linearly with the increment of the C-band lasing wavelength. The L-band gain dynamic range decreases with the increment of the cavity loss. By combining two different levels of cavity loss, the gain dynamic range of 10 dB from 11 dB to 21 dB is achieved with an average noise figure of less than 5.9 dB. The whole gain spectrum of the L-band can be used for multiple-channel amplification because the laser is created outside its signal band. OCIS codes: 060.2410, 140.3500, 140.4480.

We present a numerical model of an [Er.sup.3-] [Tm.sup.3-] [Pr.sup.3+] codoped fiber amplifier pumped with an 800 nm laser for the first time to the best of our knowledge. The rate and power propagation equations are solved numerically, and the dependence of the gains at 1310, 1470, and 1530nm windows on the active ion concentrations and fiber length are calculated. The results show that with pump power of 20 mW, when [Pr.sup.3+]-[Tm.sup.3+]-[Er.sup.3+] concentrations are around 2.0 x [10.sup.24], 2.0 x [10.sup.24], and 2.26 x [10.sup.24] (ions/[m.sup.3]), respectively, the signals at 1310, 1470, and 1530 nm windows may be equally amplified in the active fiber with a length of 1.3 m. OCIS codes: 060.4510, 060.2320.

We measured the carrier concentration distribution of gradient-doped GaAs/GaAlAs epilayers grown by molecular beam epitaxy before and after annealing at 600[degrees]C, using electrochemical capacitance voltage profiling, to investigate the internal variation of transmission-mode GaAs photocathodes arising from the annealing process. The results show that the carrier concentration increased after annealing. As a result, the total band-bending energy in the gradient-doped GaAs emission layer increased by 25.24% after annealing, which improves the photoexcited electron movement toward the surface. On the other hand, the annealing process resulted in a worse carrier concentration discrepancy between the GaAs and the GaAlAs, which causes a lower back interface potential barrier, decreasing the amount of high-energy photoelectrons. OCIS codes: 160.2100, 250.0250.

Three crystals used in solid-state lasers, namely, yttrium aluminum garnet (YAG), yttrium orthovanadate (YV[O.sub.4]), and gadolinium calcium oxoborate (GdCOB), were investigated to determine the influence of dopants on their thermal diffusivity. The thermal diffusivity was measured by thermal wave method with a signal detection based on mirage effect. The YAG crystals were doped with Yb or V, the YV[O.sub.4] with Nd or Ca and Tm, and the GdCOB crystals contained Nd or Yb. In all cases, the doping caused a decrease in thermal diffusivity. The analysis of complementary measurements of ultrasound velocity changes caused by dopants leads to the conclusion that impurities create phonon scattering centers. This additional scattering reduces the phonon mean free path and accordingly results in the decrease of the thermal diffusivity of the crystal. The influence of doping on lattice parameters was investigated, additionally. OCIS codes: 160.0160, 160.1190, 160.3380, 160.5690.

The lifetimes of the individual fluorescing lines from the terbium-doped dipicolinic acid (DPA) complex have been measured and reported, for the first time to our knowledge. These lifetimes have been measured as a function of terbium and dipicolinic acid concentration, solvent pH, and solvent composition for water, HCl, and sodium acetate buffer solutions. Fluorescence lifetimes over the range from 0.75 to 1.07 ms were measured. The maximum fluorescence was obtained for distilled water solutions. OCIS codes: 300.6280, 280.1545.

Series of samples of lightly Ga-doped CdO thin films (3%, 6%, and 9%) have been prepared by evaporation method on glass substrate. The prepared films were characterised by X-ray diffraction (XRD), UV-VIS-NIR absorption spectroscopy, and de-electrical measurements. The investigation shows that Ga doping widens the energygap of CdO. The optical properties were easily explained by using Tauc et al. band-to-band transitions and classical Drude theory. The electrical behaviour of the samples shows that they are degenerate semiconductors. The 6% Ga-doped CdO sample shows increase its mobility by 3.2 times, increase its conductivity by 1.5 times, increase its intrinsic bandgap, and a slight increase its transmittance relative to undoped CdO film. Explanation was given concerning these variations. From transparent conducting oxide (TCO) point of view, Ga is not sufficiently effective for CdO doping comparing to other dopants like In, Sn, Sc, and Y. Keywords: Optical properties; Gallium-cadmium oxide; Ga-doped CdO; Mobility; Oxides; Degenerate semiconductors

The effect of nitrogen doping on the behavior of field emission, surface energy and the band structure of strontium titanate (SrTi[O.sub.3]) thin films coated on silicon tip arrays is examined. The optimal 50%-nitrogen partial pressure might improve the threshold field of electron emission of the SrTi[O.sub.3] films accompanied with narrowed band gap and lowered surface energy.

We compared two reflection-mode negative electron affinity (NEA) GaAs photocathode samples that are grown by molecular beam epitaxy with p-type beryllium doping. One sample is uniform doping, and another is gradient doping. Experimental curves of spectral response sensitivity and quantum efficiency are obtained. The thicknesses of the two cathodes are both 2.6 [micro]m. The integrated sensitivity of the uniform doping one is 1966 [micro]A/lm, and that of the gradient-doping one is 2421 [micro]A/lm. The escape probability and diffusion length are fitted from the spectral response curves. For the uniform-doping sample, the escape probability is 0.45 and the diffusion length is 5 [micro]m. For the gradient-doping sample, the escape probability is 0.55 and the diffusion length is 5.5 [micro]m. OCIS codes: 0160.2100, 250.0250.

The generation of multiple waves during near-oblique incidence of a 532 nm weakly focused beam on photorefractive iron-doped lithium niobate in a typical reflection geometry configuration is studied. It is shown that these waves are produced through two-wave coupling (self-diffraction) and four-wave mixing (parametric diffraction). One of these waves, the stimulated photorefractive backscatter produced from parametric diffraction, contains the self-phase conjugate. The dynamics of six-wave mixing and its dependence on crystal parameters, angle of incidence, and pump power are analyzed. What we believe to be a novel order analysis of the interaction equations provides further insight into experimental observations in the steady state. The quality of the backscatter is evaluated through image restoration, interference experiments, and visibility measurement. Reduction of two-wave coupling may significantly improve the quality of the self-phase conjugate. OCIS codes: 190.7070, 190.4380, 190.5330, 190.5040.

A novel architecture was designed by combining the biocompatibility of chitosan (CS) and excellent conductivity of carbon nanofiber (CNF). The controllable electrodeposition of soluble CNF-doped CS colloidal solution formed a robust CNF-CS nanocomposite film with good biocompatibility for the immobilization and cytosensing of K562 cells on an electrode. The formed architecture was characterized using scanning electron microscopic, infrared spectrum, contact angle, and thermogravimetric analyses. The adhesion of K562 cells on the nanocomposite film-modified electrode could be followed with electrochemical impedance spectroscopy and cyclic voltammetry. The presence of CNF facilitated the electrochemical behavior of K562 cells. The impedance of electronic transduction was related to the amount of the adhered cells, producing a highly sensitive impedance sensor for K562 cells ranging from 5 x [10.sup.3] to 5.0 x [10.sup.7] cells [mL.sup.-1] with a limit of detection of 1 x [10.sup.3] cells [mL.sup.-1]. This work suggested a strategy to prepare a biocompatible and conductive interface for immobilization and electrochemical detection of cells and opened a way for the application of CNF in cytosensing.

The analytical and numerical analysis of a dopant dynamics in a delta-doped area of a multilayer structure is prepared by using a 'macroapproach'. The spreading of a delta-layer is estimated for an example of specific materials of a multilayer structure with a delta-layer.

The control of Al concentration in the polymeric precursors is essential in the synthesis of single-crystalline nanowires of [Si.sub.3][N.sub.4] by pyrolysis. The Aluminium-doping has significant effect on the emission behavior of the nanowires.

Deep level transient spectroscopy was used to characterize dominant electron trap in as-grown SiC epilayers. Electron traps, namely E1 and [Z.sub.1] were observed with [Z.sub.1] being the dominant level.

Ultrahigh-temperature solid-state microwave annealing was performed on [Al.sup.+]- and [P.sup.+]- implanted 4H-SiC. The results indicated the effectiveness of microwave annealing in both activating the implanted dopants and reducing the implantation generated defects in the SiC material.

Oxygen-doped gallium arsenide crystals were investigated by Fourier transform infrared spectroscopy. Samples with Fermi level about 0.4 eV below the conduction band showed under thermal equilibrium conditions and the optically induced conversion experiment confirm that the absorption strengths of the two bands differ by 15%.

Numerous experiments are conducted to study the characteristics of the plasma doping of various semiconductors, which are found to exhibit low energy, as well as ion implantation to form ultrashallow junctions. The analysis reveals that the shape of the bias waveform, as well as the aspect ratio of the reactor, highly influences the angular uniformity of ion energy and energy distributions (IEADs).

Judd-Ofelt (JO) analysis of spectroscopic property of [Er.sup.3+] in congruent and near-stoichiometric Zn/Er-codoped LiNb[o.sub.3] crystals was carried out. The results show that the vapor transport equilibration (VTE) treatment has a little effect on the fluorescence branch ratio but affects JO parameters, oscillator strength and electron transition probability in a large way.

Various studies are conducted to analyze carrier illumination (CI), a photoelectrothermal modulated optical reflectance (PMOR) technique that is used for one dimensional active doping profile characterization of ultrashallow junctions. The described method makes use of the power curve's first derivative at low, as well as high illumination powers, but is still not very reliable, as it has a limited extraction range.

A model, used for the calculation of glass transition temperature as a function of material composition, is devised to study the effects of Al and Cu doping on the crystallization properties of several phase change materials, like SbTe and GeSb. The results of the analysis show that Al doping leads to a tremendous increase in the glass transition temperature of the substance, though it decreases with the doping of Cu metal.

The process of photoelectrochemical etching is employed to comparatively study the properties of nanotextured high density Mg-doped and undoped GaN in the temperature dependent photoluminescence (PL). The analysis reveals that an increase in the potential fluctuation created by the nanotexurization process increases the carrier localization in the substances, which explains the observed asymmetric S-shaped behavior in the GaN compounds.

The dopant characterization of the processed fin structures for fin field-effect transistor (FinFET), which is considered to be a function of the implantation conditions, is examined. The various simulations suggest that the various techniques used in the study can be combined with implantation for further optimization of FinFET processing parameters.

The variation of the quantum-yield curves of reflection-mode and transmission-mode GaAs photocathodes under illumination is analyzed. The quantum-efficiency equation is revised for the reflection-mode photocathodes, based on the two-minima diffusion model and the fit of the escape probability, and it is used to describe the variation of their yield curves.

The effects of double-halo (DH) and single-halo or lateral asymmetric channel (LAC) doping on the subthreshold analog performance of 100-nm CMOS devices are investigated. The results have shown that the CMOS amplifiers made with the halo implanted devices have higher voltage gain over their conventional counterpart and the voltage gain has improved even when LAS doping is made on both the p- and n-channel devices of the amplifier.

The deposition of in situ boron-doped polycrystalline silicon-germanium (poly-SiGe) films in a conventional low-pressure chemical-vapor deposition reactor has been characterized using the design of experiments method. The dependencies of deposition rate, resistivity, average residual stress, strain gradient, and wet etch rate in hydrogen peroxide solution are presented. Structural layer requirements for general microelectromechanical system applications can be met within the process temperature constraint imposed by complementary metal-oxide-semiconductor (CMOS) electronics. However, residual stress and strain gradient requirements for inertial sensor applications will be difficult to meet with a single homogeneous layer of poly-SiGe that is about 2 [micro]m thick. By correlating stress depth profile measurements with cross-sectional transmission electron microscopy images, we conclude that the large strain gradient is due to highly compressive stress in the lower (initially deposited) region of the film. For films deposited at very low temperature (near the range of amorphous film deposition), in situ boron doping enhances film crystallinity and reduces the strain gradient. Index Terms--Design of experiments, low-pressure chemical-vapor deposition (LPCVD), microelectromechanical systems (MEMS), microstructure, poly-SiGe, process integration, strain gradient.

The coupled rate equation of a simple three-level model was solved to investigate the physical mechanism of the saturation process of [Cr.sup.4+]:YAG for different pulse lengths. Results reveal that the ratio of [sigma]GSA/[sigma]ESA for crystalline [Cr.sup.4+]:YAG at 1.064 [mu]m ranged between 3.8 plusminus 0.2 and 4.7 plusminus 0.2.

The effects of Al doping on electromigration in damascene Cu interconnects is reported. It is suggested that the doped Al affects the electromigration-induced Cu diffusion but does not affect the driving force.

Study is presented in which the gain and threshold characteristics of three quantum dot laser structures that are identical except for the level of modulation doping are measured. It is demonstrated that p doping leads to a higher modal gain at a fixed current density.

The band structure and the intersubband absorption in a V-groove-quantum-wire are calculated with respect to doping concentration, geometry and temperature. It is suggested that the technological parameters can be used to tailor and adjust the absorption spectra for various applications in the terahertz spectral range.

The study focuses on the effects of a gold bulk contamination on the performances of boron doped p-type crystalline solar cells made from contaminated silicon wafers, which varies for different base doping levels and different kinds of materials. This process is extremely useful because of its hydrogenation effects, though the presence of impurities in such materials containing large densities of defects lead to several undesired impurity-defect interactions.

The isothermal gas/solid equilibrium kinetics for Nb-doped Ti[O.sub.2] is reported at elevated temperatures within narrow ranges of oxygen activity and the equilibrium kinetics is monitored using electrical conductivity measurements. The chemical diffusion coefficient in strongly reduced conditions has exhibited negative temperature dependence, indicating that under these conditions transport in a chemical potential gradient is consistent with metallic charge transport.

The electrical conductivity and thermoelectric power for Nb-doped Ti[O.sub.2] are reported at elevated temperatures in the gas phase of controlled oxygen activity. The equilibrium constant is determined for the formation of oxygen vacancies and titanium vacancies for Nb-doped Ti[O.sub.2] and the results have shown that in reduced conditions the Nb-doped Ti[O.sub.2] exhibits metallic-type conductivity.

An investigation was conducted to study the effect of rapid-thermal processing (RTP) ambients on the formation of oxygen precipitates and denuded zone (DZ) in heavily boron-doped (HB) Czochralski (Cz) silicon by a low-high (L-H) two-step annealing. The findings suggested that after the L-H two step annealing, there was a high density of bulk microdefects and no observable DZ was formed near the surface in HB Cz silicon wafers preannealed by the RTP in Ar ambient.

Experiments were conducted to investigate the locking dislocations by oxygen in Czochralski silicon (Cz-Si) with different concentrations of shallow dopants. In the 450-550 degree Celsius temperature range, the gradient of the rise in dislocation unlocking stress was found to be approximately a factor of 3 higher in highly antimony doped n-type Cz-Si than in low boron doped p-type Cz-Si.

Nickel-doped and nitrogen-doped carbon nanocones with various amounts of buckling that feature square-planar, (approximate) tetrahedral, and octahedral coordination are designed. The optimized geometries and electronic structures of these novel metallocarbon complexes are calculated by employing the B3LYP and GGA-BLYP (ADF) exchange-correlation functionals.

A method for estimating the positions of charge transfer (CT) bands in [Eu.sup.3+]-doped complex crystals is reported. The relationship between the experimental CT energies and calculated environmental factors is established by an empirical formula.

High-efficiency boron- and gallium-doped multicrystalline silicon (mc-Si) cells are fabricated and compared. The quality of three different boron-doped mc-Si ingots and one gallium-doped mc-Si ingot is investigated and compared by means of lifetime measurements and solar cell efficiencies.

An investigation on the nanostructure and photoluminescence of polycrystalline Er-doped Y2O3 thin films, deposited by radical-enhanced atomic layer deposition (ALD) is conducted. From the energy loss spectroscopy (EELS) mapping of Er in Y2O3, results reveal that Er is distributed in layers separated by layers of Y2O3 with the separation distance between the layers controlled by the ratio of Y2O3:Er2O3 cycles during the deposition.

An investigation on the defect centers generated in crystalline silicon by MeV Si implants is conducted by a combination of photoluminescence, variable-energy positron annihilation measurements, depth profiling by etching, annealing studies, and the dependence on impurities. The 835 meB band occurs at a low concentration of small vacancy clusters in the 'near-surface' region, which appear to agglomerate under annealing into the larger vacancy clusters that produce the 1062.3 meV band.

An investigation on the 1.3 [mu]m fluorescence shifts of [Pr.sup.3+] or [Dy.sup.3+] ion doped glasses is conducted in terms of the peak fluorescence wavelength (PFW) shift. The quenching of luminescence dominates the reshift of PFW with increasing doping concentration.

A comparison of the electrical properties of TaN-HfO[sub 2]-Ge MOS devices built on different types of substrates, including the CET, gate leakage current, hysteresis, slow trap density, C-V frequency dispersion, breakdown voltage and PMA effect, is presented. The dependence of the device performance on the substrate indicates the crucial role of substrate doping in the reactions at the interface, and two competing processes namely oxide growth and oxide desorption are suggested to determine the formation of interfacial layer and affect Ge updiffusion.

An analytical model for the base transit time for an exponentially doped base is developed assuming a small change in electron concentration in the base of a bipolar junction transistor at high injection from its low injection value. The base transit time calculated analytically is compared with simulation and numerical results as well as experimental data in order to demonstrate the validity of the assumptions. The base transit time is found to be different if the field dependent mobility is considered.