Study Of Defects In Silicon Research Articles

Study of the development of defects in Si PIN diodes exposed to 23 GeV/c protons

Studying the development of crystallographic defects in PIN diodes is the focus of the RD-50 (CERN) research project. The study was carried out on Si PIN diodes manufactured and used in the Czech Republic. The Si PIN diodes were irradiated with 23 GeV/c protons at doses ranging from 0.5 to 43 Gy. The Si PIN diodes were calibrated in a 23 GeV/c proton source [1], and the energy traps of the defects produced were measured by the DLTS method. The IV characteristics and the parameters of the defects were studied. The 23 GeV/c protons produce typical crystallographic defects and, at higher doses, bring about their regrouping thus giving rise to a new generation of defects. Defects are classified by their energy levels in the forbidden band from the conduction band. The mechanism influencing the parameters of the defects is discussed. The study of defects in silicon is important for silicon-based electronic elements used in cosmic research because of their effects on the operability and reliability of electronic equipment installed in satellites. Another application is the dosimetry measurements involving various types of particle accelerators.

Photoluminescence and infrared spectroscopy for the study of defects in silicon for photovoltaic applications

It is widely known that photoluminescence (PL) and infrared (IR) spectroscopies are among the experimental tools extensively used in the last decades for the study of impurities and defects in silicon for both microelectronic and photovoltaic applications. This review paper reports the main historical achievements and recent developments obtained in this field by PL and IR, paying particular attention to the most useful data for the study of defects in silicon for photovoltaic applications.

Positron-Annihilation-Spectroscopy Study of Proton-Induced Defects in Silicon

General approaches are considered to the structural characterization of defects in solids by positron-annihilation spectroscopy. Positron annihilation is studied experimentally on proton-irradiated silicon wafers made to different specifications, using the angular distribution of annihilation photons. A parabolic and a Gaussian component are identified in the distribution curves. They are associated with the annihilation of Wheeler states in the bulk and near Si-ion cores, respectively. The densities of radiation-induced defects are deduced from the experimental data.

Modified neglect of diatomic overlap parametrization of oxygen: A cluster study of oxygen defects in silicon

We present a parametrization of oxygen within the framework of the modified neglect of diatomic overlap (MNDO) technique. The atomic structure and formation energy of a oxygen defect in silicon are studied as a test of the reparametrized MNDO technique. We find that the geometry and the associated formation energy are in good agreement with experiment as well as with results of ab initio calculations. Even the calculations based on the MNDO technique are by 2 or 3 orders of magnitude less expensive than ab initio calculations.

Quantum Monte Carlo Study of Silicon Self-interstitial Defects

We give a brief description of the variational and diffusion quantum Monte Carlo methods and their application to the study of self-interstitial defects in silicon. The diffusion quantum Monte Carlo calculations give formation energies for the most stable defects of about 4.9 eV, which is considerably larger than the values obtained in density functional theory methods. The quantum Monte Carlo results indicate a value for the formation+migration energy of the self-interstitial contribution to self-diffusion of about 5 eV, which is consistent with the experimental data.

Recent Advances in the Application of Slow Positron Beams to the Study of Ion Implantation Defects in Silicon

Recent Advances in the Application of Slow Positron Beams to the Study of Ion Implantation Defects in Silicon

EPR of defects in semiconductors: Past, present, future

Important physical concepts learned from early EPR studies of defects in silicon are reviewed. Highlighted are the studies of shallow effective-mass-like donors and acceptors by Feher, of deep transition-element impurities by Ludwig and Woodbury, and of vacancies and interstitials by Watkins et al. It is shown that the concepts learned in silicon translate remarkably well to corresponding defects in the other elemental and compound semiconductors. The introduction of sensitive optical and electrical detection methods during the intervening years, and the recent progress in single-defect detection insure the continued vital role of EPR in the future.

Study of Point Defects in Silicon by Means of Positron Annihilation with Core Electrons

High momentum parts of the momentum distribution of annihilation photons are examined both theoretically and experimentally for vacancies and vacancy-oxygen complexes in Si, Atomic relaxations in the neighbourhood of the defects are taken into account, Theoretical calculations are compared with measurements performed on undefected and electron irradiated Czochralski grown and float-zone Si samples.

Temperature Dependent Electron Beam Induced Current Study of Defects in Silicon

A new computer-aided electron beam induced current system was developed which makes it possible to obtain two-dimensional mapping of the absolute magnitudes of electron beam induced current signals over the temperature range 15 K-400 K. Electronic states of defects in cast silicon and deformation-induced dislocations in float-zone silicon were investigated from the analyses of temperature dependencies of electron beam induced current contrasts of the defects measured with the system. Electron beam induced current active defects in cast Si were identified to be Fe impurity atoms or Fe—B pairs incorporated at the dislocation core depending on the cooling rate of a crystal. Dislocations in float-zone silicon were shown to have an energy leve1 for carrier recombination in the lower half of the band gap. PACS numbers: 71.55.Fr, 72.80.Cw

Role of free carriers in the application of optically detected magnetic resonance for studies of defects in silicon

The influence of free carriers on optically detected magnetic resonance (ODMR) signals for defects in silicon is discussed. The presence of free carriers induces a strong background signal in the ODMR spectrum due to carrier heating effects in a microwave field. This background signal often obscures a possible detection of a defect-related magnetic resonance signal and is therefore highly undesirable. To avoid this problem, a delayed ODMR (D-ODMR) technique is employed. On the other hand, the presence of free carriers provides a medium for a possible ODMR detection of nonradiative defects. This is realized by a shunt pass of carrier recombination at such defects, which competes with the radiative carrier recombinations detected optically, and gives rise to negative ODMR signals for the defects responsible for the nonradiative recombination. Typical examples from recent studies of these different cases of defects in silicon are demonstrated.

Tight-binding molecular-dynamics study of defects in silicon.

A tight-binding molecular-dynamics scheme is shown to have the efficiency and accuracy to study complex Si systems. We first establish the reliability of the scheme by showing that simulation results of liquid Si are nearly identical to ab initio (Car-Parrinello) results. The ability of the method to study complex systems is demonstrated by calculating defect formation energies and atomic configurations around vacancies and self-interstitials, with simulation unit cells of up to 512 atoms. The calculated formation energies compare well with first-principles results.

New Developments in the Dynamic Mechanical Analysis of Thin-Layer Materials

AbstractThe vibrating-membrane configuration represents an important new approach to the dynamic mechanical analysis of thin-layer materials. The method offers a convenient capability for high-resolution stress measurements over a wide temperature range, and can be combined if desired with internal friction measurements for the detection of defect-related relaxation peaks. Illustrative results are given for the thermomechanical behavior of silicon, silicon carbide, and synthetic diamond membranes, and for the moisture swelling of polyimide films. A detailed study of hydrogen-boron point defects in silicon is in progress, using both internal stress and internal friction measurements, and work on membranes has been supplemented significantly by the use of vibrating-string and ultra-thin vibrating-reed samples.

Study of defects in silicon after low energy H+ implantation by DLTS measurements

The introduction and annealing of defect states in silicon implanted with H+ ions are studied by capacitance transient spectroscopy (DLTS) on Schottky barrier structures. Several of the observed defect levels can be correlated with those identified in electron-irradiated silicon. Passivation of the defect states by hydrogen atoms is observed after 200 °C annealing. A tentative interpretation of the observed level as deduced from the annealing process is proposed. La creation et la guerison des defauts d'implantation d'ions H+ dans le silicium sont etudiees sur des structures a barriere de Schottky par des mesures de capacite transitoire (DLTS). Certains defauts observes peuvent ětre correles aux defauts identifies dans le silicium irradie par electrons. Une neutralisation des defauts par les atomes d'hydrogene est observee apres un recuit thermique a 200 °C. Une tentative d'interpretation des defauts observes est proposee a partir de l'etudo de leur guerison.

STUDY OF THE DEFECTS IN SILICON PRODUCED BY HIGH TEMPERATURE ELECTRON IRRADIATION

A study of defects in silicon produced by hightemperature electron irradiation was carried out. It was found that the introduction rate of defect increased with the temperature at which the samples were irradiated by electron. After the temperature reached an "extreme" value Tm, the introduction rate of defect began to decrease. The Tm value was related to the annealing activation energy of defect. It was also found that the density of E3 (Ec-0.36 eV) defects greatly increased in hightemperature electron irradiation. When electron irradiation was carried out at 330℃, the density of E3 defects was about 6 times as large as that at room temperature. The possible structure of the E3 defect is multivacancy-oxygen complex.

Excitation Spectroscopy on Silicon Using Color Center Lasers Study of the Thermally Induced P Line (0.767eV) Defect

AbstractRecently developed tunable color center lasers allow to extend the experimental technique of excitation spectroscopy to the 1–2 μm region. This spectral range is of special interest for the study of luminescent defects in silicon. We discuss the color center laser systems available at present and their application to defect spectroscopy. As an example, results on the 0.767 eV (P line) defect in silicon are presented. Excitation spectroscopy reveals several high lying excited electronic states. They are interpreted as effective—mass—like states of a pseudo-donor with an ionization energy of 34.3 meV.

High voltage electron microscope study of defects in silicon

In-situ observation of defect formation in Fz and Cz silicon with (111) orientation by electron irradiation has been performed at temperatures between -100°C and 550°C using a 2 MeV high voltage electron microscope. Two kinds of interstitial type faulted dislocation loops are formed with and without an incubation period, respectively. The former appears in the region localized at the electron entrance surface, and the latter mainly localized at the electron exit surface. Linear defects, which appear near the electron exit surface, are also observed. Annealing experiments of these secondary defects were carried out around 800°C, and the point defect species which contribute to the shrinkage of the loops were identified as the vacancy, and the mean activation energy of 3.5 eV was obtained for self diffusion.

EPR Studies of defects in silicon

AbstractElectron and neutron irradiated, plastically deformed silicon has been studied by EPR. Irradiation resulted in a strong decrease of the EPR spectra produced by the deformation and in the appearance of a new EPR center at dislocations. Thermal annealing lead to a reestablishment of the formerly present dislocation spectra. As most probable explanation is proposed a change of the dislocation strain field by irradiation induced point defect iclusters. – EPR investigations of iron in boron doped Si demonstrated the pairing of all nterstitial iron in FeB pairs during room temperature storage. Thermal treatment at temperatures higher than 100°C lead to the reappearance of Fe. Therefore the time limiting factor for the annealing of FeB pairs should be the precipitation of interstitial iron.

Diffuse X-Ray Scattering for the Study of Defects in Silicon

ABSTRACTX-ray diffuse scattering can be used to study the size, concentration, and nature of lattice defects and defect clusters in crystalline materials. The availability of analytical models and detailed numerical calculations for the “Huang” diffuse scattering close to Bragg reflections and the “asymptotic” diffuse scattering at somewhat larger distances from Bragg reflections has made it possible to carry out detailed analyses of the intensity and angular distribution of the diffuse scattering in terms of specific defect parameters. Accordingly, diffuse scattering has been used to study point defects, dislocation loops, and precipitates in metals, semiconductors, and insulators and has provided information on defect geometries, size distributions, and concentrations. In this paper, the theoretical framework necessary for the interpretation of the “Huang” and “asymptotic” diffuse scattering from defect clusters is presented and examples of diffuse scattering calculations for defects in silicon are given. Diffuse scattering from clustered defects in silicon is discussed in terms of the type of information available from this scattering and the relative merits of diffuse scattering as an investigative tool for defect clusters. Diffuse scattering analysis techniques for the determination of separate size distributions for vacancy and interstitial dislocation loops in silicon are presented and applied to diffuse scattering measurements on neutron irradiated silicon. Dislocation loop densities and sizes determined in the as-irradiated state and after thermal anneals are compared with electron microscopy results.

Photoconductivity Studies of Defects in Silicon: Divacancy-Associated Energy Levels

Divacancy associated energy levels in electron irradiated n-type Si identified by photoconductivity study employing uniaxial stress induced reorientation and polarized light