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An accurate implantation profile describing continuous energy spectrum positrons emitted from a [super 22]Na source is proposed and experimentally verified for silicon targets. An optimal fit of the model to the experimental data requires that the parameter defining the mean depth of the Makhov profile (usually denoted r) is energy dependent.

The applications of the intrinsic gettering (IG) processes based on rapid thermal annealing (RTA) in germanium-doped Czochralski (GCZ) silicon wafers are examined. The phenomena is attributed to the formation of Ge-V-related complexes by the germanium doping in CZ silicon during RTA pretreatments and it is shown that the GCZ silicon wafers can be used for large scale integration (LSI) fabrication.

Electron spin-resonance (ESR) spectroscopy is used to study the properties of conduction electrons in Pd-doped Si nanocrystals embedded in insulating glass matrices. The temperature and P concentration dependence of ESR spectra has shown that the behavior of the conduction electron signal is much different from that of Pd-doped bulk Si crystals.

Spatially resolved laser-induced breakdown spectroscopy (SRLIBS) was used for the characterization of aluminum and silicon in nickel-based alloys. The very low invasiveness of the technique was one of the figures of merit of LIBS; however, the relative complexity of the instrument often hindered the widely acceptance of LIBS. Spatially resolved LIBS could provide accuracy and precision comparable to those obtained with temporally resolved LIBS (TRLIBS). In the nongated spatially resolved LIBS, the maximum atomic emission could be obtained with relative low continuum background emission at optimum observation spatial position. The study was done with a Nd:YAG laser at 532 nm, 3.0 mJ laser energy, and 0.2 mbar in argon. The experimental results obtained under optimum conditions were compared to those obtained with TRLIBS. SRLIBS gave reliable results without the tedious optimization of the delay time and gate width.

[sup.29]Si MAS NMR spectroscopy on samples of 10-[Angstrom] phase synthesized from oxides (6.0 GPa/600 [degrees]C/400 h) and from partial transformation of talc (6.5 GPa/650 [degrees]C/12.5 h) reveals that this phase contains [Q.sup.2]-type Si sites in a ratio [Q.sup.3]:[Q.sup.2] of 5.33:1. It is proposed that the [Q.sup.2] arise from adjacent vacancies in the tetrahedral sheets for which charge balance is most likely achieved by hydroxylation via a hydrogamet-like substitution involving the formation of [Q.sup.2] silanol groups. Variable-contact-time [sup.29]Si {[sup.1]H} CP/MAS NMR spectra of the talc/10-[Angstrom] phase product support the assignment of [Q.sup.2] Si to the proposed Si[O.sub.3](OH) groups. Electron microprobe analysis, including oxygen, gives the following empirical formula normalized to three Mg apfu and inferring a hydrogarnet component Si [right arrow] 4H associated with Si vacancies: [Mg.sub.3][Si.sub.3.83(8)][O.sub.9.32][(OH).sub.2.68].1.1(4)[H.sub.2]O. The observed Mg:Si indicates a significant Si deficiency relative to talc. Comparison of the [sup.29]Si MAS NMR and microprobe data indicates that Si vacancies likely occur as single isolated entities, rather than as pairs or clusters, and that between 1 in 18 and 1 in 23 Si sites is vacant. The results suggest new and intriguing possibilities for the incorporation of excess H into the 10-[Angstrom] phase and, potentially, other phyllosilicates under upper-mantle conditions. Keywords: 10-[Angstrom] phase, Si vacancies, [sup.29]Si NMR spectroscopy, silanol

Two types of paramagnetic defects in the surface oxide layer of ultrafine Si particles, temporarily named an EX(sub L) center and an EX(sub H) center, are investigated by Electron spin resonance (ESR). The relationship between ESR signals and infrared spectra is studied.

The effect of doping level and illumination on the formation of n-type porous silicon is studied with the help of high-resolution x-ray diffraction. A degradation of the crystal quality, increasing with a decrease of the material doping level is observed.

A study is conducted to examine the accumulation of damage and the development of mechanical strain in crystalline Si (c-Si) by O and N ion implantation to doses up to 4 x 10(sub 17) cn\m (super -2) at elevated temperature by using Rutherford backscattering spectrometry. The conclusion states that an ion beam induced annealing process participate in the formation of the near-surface damage-free layer during high temperature implantation of c-Si.

Crystalline silicon was analyzed to determine the thermo-optic coefficient.

Research into static and dynamic (hyper)polarizabilities of SiH3 radical is presented. It is suggested that threefold coordinated Si centres may be responsible for the observed second harmonic generation in a-SiO2.

Issues concerning the spectral responses of photovoltaic devices based on metal/porous silicon (PS)/silicon (Si) sandwich structures are discussed. The energy conversion efficiency of the photovoltaic devices can be increased by controlling the structure of the porous silicon films.

A two-dimensional model of a strained Si/Si1-xGex transistor with delta-doped layers has been proposed. The model was used to analyze the effects of different construction-band offsets and variation of the distance between the Si channel and an n-type delta-doped layer, and the thickness of the delta-doped layer at room temperature. The results showed that a large conduction-band offset, or a large Ge concentration, confines electrons more strongly to the Si channel.

The room temperature visible photoluminescence of wide-band gap hydrogenated amorphous thin films is described. The films were prepared in silane microwave plasma strongly diluted with He under electron resonance conditions by the MW ECR PE CVD method. The films were characterized by optical and infrared absorption, hydrogen thermal desorption, and Raman scattering. The results showed two types of photoluminescence: one related with oligosilanes and the other with electron-hole recombination in tail states.

Research was conducted to examine the He-implantation induced defects in Si by means of Doppler broadening measurements with a slow positron beam. Positron annihilation spectroscopy calculations covered the initial distribution of vacancy-like defects for samples implanted at two doses and the evolution of vacancy-like defects during isothermal annealing at a temperature near the threshold of helium desorption. Results indicate that the differentiation in the behavior leading to cavities in Si may possibly start above the annealing temperature of 250 degrees C.

A deduction of the primary photodissociation mechanism of Si2H6 at 193 nm was made by photoproduct detection by laser-induced fluorescence (LIF) and time-resolved mass spectrometry techniques. Observation of the Si2H6 was conducted by the LIF method. No signal has been detected from SiH3, Si2H5, Si2H3 and Si2H4 in 193 nm photolysis. The importance of H2 elimination processes in Si2H6 produced in 193 nm photolysis was suggested by existing data combination.

A porous silicon film which underwent heat treatment in an argon atmosphere was studied by positron lifetime and Doppler broadening spectroscopies. Heating between 300 and 500 deg C increased the mass of the film by 17% because of oxygen uptake and the concentration of open volume defecs related to the formation of an oxide layer on the silicon nanocrystallites increased threefold. Between 600 and 1000 deg C, their concentration declined gradually to 50% of the original concentration.

A study was conducted to examine ellipsometrically the optical spectra of silicon between 300 and 1200 K in the spectral range from 2 to 4.3 eV. Several sources of measurement errors were analyzed, including the angle of incidence at lower photon energies and the overlayer thickness in the range of high absorption. Dielectric functions of pure and heavily doped silicon samples were effectively determined from 298 to 1123 K both in the visible and near-ultraviolet spectral regions.

The encapsulation of the transition metal complexes cis-Pt(NH3)2Cl2, Ru(bpy)3(2)+ and Ru(phen)3(2)+ within hydroxyapatite layers on a porous Si/Si substrate was investigated. The compounds were chosen as a consequence of their biological activity (cis-Pt(NH3)2Cl2) or polynucleotide binding ability (Ru(bpy)3(2)+ and Ru(phen)3(2)+). Experimental results showed that the release of the transition metal complexes into the surrounding medium through thermal heating of the complex-doped hydroxyapatite/porous Si/Si substrate can be controlled.

Organic cyano compounds such as 1,2-dicyanoethylene, 1,3-dicyanobenzene, 1,4-dicyanobenzene and 1-cyanonaphthalene have been used in enhancing the photoluminescence (PL) of oxidized porous silicon (PS). It was found that PL was dependent on the steric effects and electronic properties of the cyano compounds. Fourier transform infrared spectra revealed that surface Si-H bonds have not been altered and no new luminescent compounds have been formed on the surface of PS.

A model for the photoluminescence (PL) spectra of porous silicon has recently been proposed. The model is applied to two types of experimental results and the properties of PL spectra are investigated. The model assumes that the luminescence spectrum comes from the groups of various size particles distributed in porous silicon. The size of nanoparticles is found to obey the logarithmic normal distribution, instead of the Gaussian distribution.

The effects of anodization temperature on the formation of porous Si have been studied. The porosity, luminescence, refractive index, porous Si/bulk Si interface roughness and growth rate were monitored, and a strong reduction of roughness was achieved for low temperature anodization. The results were used in the fabrication of distributed Bragg reflectors.

Two damage regions, a near-surface vacancy-rich region Rp/2 and a buried layer near the MeV Si ion projected range Rp have been studied for gettering properties. These were quantitatively determined using secondary ion mass spectrometry and deep level transient spectroscopy methods. MeV defects were brought into expitaxial silicon doped with boron. Gettering the Rp region was found to be driven by relaxation of supersaturated Fe.

The effect of the substrate and the specific preparation conditions on the structure of submonolayer films and on the film growth mechanism were studied using two largely different substrates, native silicon and mica. The growth process of self-assembled octadecylsiloxane (ODS) monolayers was also monitored under systematic variation of the water content in the adsorbate solution and age of the adsorbate solution. Results reveal the involvement of both a continuous growth and an island-type growth in the formation of ODS monolayers. Island-type growth is strongly favored on both silicon and mica surfaces with increasing water content or increasing age of the adsorbate solution.

Effective energy loss functions for Si 2p photoelectrons were examined for the thermally cleaned Si(111), oxygen-adsorbed Si(111) and SiO2 surfaces by the analysis of the reflection electron energy loss spectroscopy spectra utilizing the extended Landau theory. Findings showed that the effective energy loss functions derived for the clean Si(111) surface are significantly affected by the oxygen adsorption. The x-ray photoelectron spectroscopy source functions from the clean and oxygen-adsorbed Si(111) surfaces indicate a small hump caused by the chemical shift by the oxygen adsorption at the tail of the lower kinetic energy side of the Si 2p peak from the oxygen-adsorbed Si surface.

The strong photoluminescence of SiO(sub x):H produced by plasma enhanced chemical vapor deposition was systematically investigated including infrared and micro-Raman spectra. Results showed that each photoluminescence spectrum is composed of two Gaussian components, a main band and a shoulder. The main band may be due to amorphous silicon clusters embedded in the SiO(sub x) network and its redshift with annealing temperature may be caused by expansion of the silicon clusters. The shoulder remains at approximately 835 nm in spite of the annealing temperature and may be caused by luminescent defect centers.

The use of Raman techniques to detect interstitial O(sub2) molecules in bulk samples of highly oxygen-saturated silica, is investigated. Research also aimed to determine the concentrations of O(sub2) in silicas, compared with the Raman signal intensity of gaseous O(sub2). Approximate conversion factors were provided to convert related O(sub2) luminescence intensity into absolute O(sub2) concentration units.

Porous silicon (PS) has potential applications in 'all silicon optoelectronics'. A structural investigation of thin PS layers and multilayers has been undertaken, using high resolution x-ray diffraction. Information can be deduced about porous layer parameters including porosity, lattice parameter, interface transition and thickness, in a nondestructive way. Several thickness fringes, and some satellites were observed.

Radiative recombination of confined excitons (quantum confinement) could make the most significant contribution to the luminescence spectrum of silicon nanoclusters. Research using the effective mass approximation model allowed the luminescence spectra to be modeled to a good fit. This model was found to be suitable as an approximate method for estimating the modified band gap of the Si clusters over the size range 20 angstroms to 80 angstroms.

Variable angle of incidence spectroscopic ellipsometry between 0.75 eV and 6.5 eV was conducted to examine the optical constant spectra of silicon and thermally grown silicon dioxide. The optical constants for thermal silicon dioxide were found to be about 0.4% higher in index than bulk glasseous SiO2 values. Results also show that the silicon optical constants are in agreement with previous ellipsometric, long wavelength prism and near band gap transmission measurements.

Research was conducted to examine the accurate heats of formation for SiFn and SiFn+ for n = 1-4, which are critical in modeling processes that are important to the semiconductor industry. Calculations for the SiFn and SiFn+ species using higher levels of theory than previously used are employed using the computed bond energies without any experimental input other than the heats of formation of F7 and SiF4 and ionization potential of Si. Results are compared with various lower levels of theory.

Amphoteric native defect reactions in silicon-doped gallium arsenide semiconductors were examined using photoluminescence analysis. The photoluminescence spectra were measured at various depths below the sample surface to yield the concentration distribution of the native defects. Results showed that large concentrations of V As and V Ga were formed in silicon-doped gallium arsenide samples annealed under gallium-rich and arsenic-rich conditions, respectively.

The antireflection properties of V-grooved gratings in (100) crystalline silicon are studied numerically by use of rigorous electromagnetic theory. This study shows that these gratings can exhibit antireflective behavior only for TM-polarized radiation. The V-grooved structures are analyzed as a function of grating period, duty cycle, and depth of a Si[O.sub.2] mask layer that is added to the tops of the V-grooved mesas. Specific antireflection grating designs (the duty cycle and depth versus the period) are presented that illustrate TM-polarized reflectivity much less than [10.sup.-3] with periods as high as 80% the wavelength of incident radiation. These designs exhibit good tolerance to fabrication errors and grating's plane deviations in a planar-diffraction mounting. OCIS codes: 310.1210, 050.1950, 260.2110, 040.6040.

Experiments were performed to investigate the mechanism of photoluminescence (PL) in porous silicon surface during the early stages of electrochemical etching and during stabilization in ethylene glycol solution. A quantum mechanical model was used to examine the relationship between the excited states of a silanone-based silicon oxyhydride triplet with green and orange-red PL emissions. The excitation and emission spectra of PL were influenced by the oxidative reactions on the porous silicon surface on which silanone-based silicon oxyhydrides were formed and transformed.

The refractive index n = 1 - [Delta] + i[Beta] of Si in the energy range 50-180 eV is investigated with angle-dependent reflectance measurements. The optical constants [Delta] and [Beta] are both determined by fitting to the Fresnel equations. The results of this method are compared with the values in the atomic tables derived from experimental data for [Beta] and implementation of the Kramers-Kronig relations for [Delta]. The samples were prepared by UV irradiation and HF:ethanol dipping to H passivate the surface. It is found that the values of [Delta] in the atomic tables are 8-15% too high in the region 50-90 eV. This is attributed to missing oscillator strength in the tabulated absorption coefficient for Si. The measured values of [Beta] for crystalline Si exhibit structure below the [L.sub.2,3] edge (99.8 eV), as was previously observed in transmission measurements of Si(111). It is also found that the method of least-squares fitting reflectance data to obtain optical constants is most effective for energies well below the edge, where [Delta] > [Beta], while for a range of energies around and above the edge, where [Delta] < [Beta], the optical constants are determined with large uncertainties. This behavior is not unique to the Si [L.sub.2,3] edge.

A gated charge-coupled device camera was employed in recording the emission spectrum exhibited by porous silicon at room temperature after pulsed laser excitation. A redshift in the porous silicon's photoluminescence with 100 microsecond time scale delay time was observed. The emission spectrum, however, did not exhibit a distorted band shape. This indicates that the redshift was caused by the spectral diffusion from the energy transfer between emitters.

The light-emitting porous silicon was treated by the rapid thermal procedure at 900-1100 degrees C under NH3 environment. The infrared absorption spectra and Auger electron spectra indicated that the surface of porous silicon was covered with a nitride-containing layer. The density of dangling bonds were observed to be quite low. The photoluminescence intensity indicated a slight decay under the laser illumination and remained almost unchanged after three months storage in ambient air.

The spectral behavior and temperature dependence of the absorption coefficient of microporous silicon films were investigated in the energy range of 1.2-3.8 eV, between 7 and 450 K. For photon energies above the direct band gap at 3.3 eV, the spectral behavior of the absorption coefficient of microporous was similar to that of crystalline silicon and its absolute value was comparable to that estimated utilizing Bruggeman effective medium approach. For lower energies, the absorption coefficient was much reduced with respect to the effective medium model prediction.

The defect band photoluminescent (PL) behavior of phosphorus-doped thin films of amorphous silicon with subgap and gap excitations was characterized as a function of temperature. Consequently, the relationship between temperature and the defect PL band generated by subgap excitation was attributed to two recombination processes. The first is possibly related to the carrier recombination at hanging bonds and band tail states. The second appears to be related to donor-defect pairs at neighboring sites.