An analytic expression for the effective transport energy in a positionally random and energetically disordered hopping system is obtained. It shown that multiple carrier jumps within pairs of occasionally close localized states strongly affect position level on scale lead to noticeable difference between most probable jumps. In with Gaussian density-of-states distribution, equilibrium mobility found be an almost factorized function temperature concentration states.

Photoluminescence excitation (PLE) spectra, measured at varying temperatures and for different luminescent energies, are applied systematically to the study of defects in $\mathrm{I}a,$ $\mathrm{I}b,$ $\mathrm{II}b,$ chemical-vapor-deposited (CVD) diamond. It is shown that green band CVD diamond films consists two distinct components. The first one attributed recombination amorphous carbon phase. second component increases with surface hydrogenation films, but an analogous remains almost...

Abstract Monte Carlo simulation techniques have been employed in the examination of anomalously-dispersive transport characteristics specimens with various energy distributions localized states. For each four studied, ‘initial slope’ dispersion parameter, α1, varies similarly temperature, and exhibits an approximately linear variation low-temperature regime. This demonstrates that such behaviour does not constitute evidence for presence a particular (e.g. exponential) distribution traps. The...

Characteristic features in photocurrent (PC) and electron paramagnetic resonance (EPR) spectra are discussed attributed to main defects the gap of optical-quality chemical vapor deposited diamond. A shoulder PC with an onset at about 2.2 eV is single-substitutional nitrogen defect (EPR P1 g=2.0024). second feature 1.3 observed on “as-grown” samples a hydrogen terminated surface. The level associated this related, disappears after oxidation diamond sample EPR g=2.0028, which was also...

A model is formulated describing trap-controlled space-charge-limited currents (SCLCs) in an organic material with a Gaussian density-of-states (DOS) distribution. It shown that SCLC not always controlled by carrier release from localized states around the Fermi level and, therefore, DOS can serve as either shallow or deep distribution of depending upon and/or current density.

We investigated the additional resonance lines in K${\mathrm{H}}_{2}$As${\mathrm{O}}_{4}$ (KDA) $^{75}\mathrm{As}$ NMR spectrum, whose appearance temperature region just above paraelectric to ferroelectric transition has been reported before. It is shown that an earlier model which assumes a bias fast electric-field-gradient fluctuations normally found phase does not give satisfactory account of experimental frequencies. Agreement with experiment attained when formation fully polarized...

The photoconductivity response time of amorphous semiconductors is examined theoretically on the basis standard definitions for free- and trapped-carrier lifetimes, experimentally a series a-${\mathrm{Si}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{C}}_{\mathit{x}}$:H alloys with x0.1. Particular attention paid to its dependence carrier generation rate temperature. As no satisfactory agreement between models experiments emerges, simple theory developed that can account experimental...

Optical absorption measurements were performed on irradiated diamonds containing different concentrations of nitrogen defects. Analysis the results suggests that single substitutional centres trap vacancies about eight times more efficiently than pairs. In diamond crystals with a low impurity content, as well in synthetic films, an undocumented IR spectrum is observed and ascribed to intrinsic

Optical transitions at the single substitutional nitrogen centre (P1) in synthetic diamond are discussed. It is shown that 4.6 eV absorption band not due to P1, but some other centre, tentatively suggested as a nitrogen-boron complex. The 4.5 photocurrent threshold assigned transition from valence ground state of P1 centre.

Abstract A series of pure bulk a-As2Se3 samples has been examined by means steady-state and transient photoconductivity techniques as well photoinduced absorption in order to clarify the requirements be met a model for distribution gap states this material. Some sources metastable defects, which probably distorted earlier measurements, are identified. The required is found broad featureless but must allow set discrete excitation energies. Klinger Karpov involving elastically soft lattice...

Post-transit photocurrent analysis, based on the time-of-flight transient photoconductivity technique, was successfully carried out for a series of amorphous selenium $(a\ensuremath{-}\mathrm{Se})$ thin films. The method allows determination density gap states beyond shallow tail from emission-dominated post-transit currents. Prominent hole and electron traps were resolved some 0.4--0.5 eV above valence-band edge 0.55--0.65 below conduction-band edge. These two represent thermally accessible...

Characterization of a series correlated electron-spin resonance (ESR) and photoluminescence (PL) lines in diamond grown by chemical vapor deposition is reported. The consists set structured PL bands the range 1.8--2.3 eV, ESR due to an $S=1$ center with $g=2.0039(1)$ $D=35.8(1) \mathrm{mT}$ at 300 K. are shown originate from defect ground state 2.24 eV below conduction band, several excited states. whole data can be interpreted terms containing neutral interstitial Ni atom divacancy.

Abstract A general relation is deduced between the density of localized states N(E) and transient photocurrent I(t) for an amorphous semiconductor exhibiting trapcontrolled electronic transport. It demonstrated that waiting-time distribution functionψ(t) related to through a Volterra integral equation, which may be solved numerically. The relative in straightforward manner from ψ(t), using approximation should not introduce more than small degree distortion. computational method applied case...

Analytical and numerical models for studying the effects of large signals on charge collection efficiency in radiation detectors are described by considering bimolecular recombination between drifting carriers, carrier trapping, space effects. First, an analytical solution is obtained assuming that field remains relatively uniform. Then continuity equations both holes electrons, Poisson’s equation across photoconductor a short pulse irradiation simultaneously solved finite difference method,...

Abstract It is shown that most features of anomalously dispersive multiple-trapping transport in amorphous semiconductors can be calculated easily and accurately when the density localized states represented by a set discrete levels. Calculation transient current, occupation conduction band trapping levels, trap parameters are known, reduces to simple matrix operations. The same holds for solution inverse 'spectroscopic' problem; is, given photocurrent, obtaining distribution states. For...

In a narrow temperature region above the transition temperature, KH2AsO4 (KDA) exhibits dielectric relaxation with characteristic frequencies near 20 Hz. Although can be explained by presence of central mode motion in KDA, possibility that crystal defects are at its origin cannot, this point, excluded. einem beschränkten Temperaturbereich oberhalb der Umwandlungstemperatur wurde eine dielektrische Relaxation mit charakteristischen Relaxationsfrequenzen um Hz beobachtet. Obwohl die aus...

The deuteron quadrupole coupling constants and asymmetry factors in single crystals of DCOOH HCOOD are found to be 161± 2 kHz, η=0.040± 0.025 165.1± 2.7 η=0.125± 0.030, respectively. These compared with free molecule crystal results others on the formate group. In addition, attention is called influence X-fragment electronegativity upon constant C–DX compounds sp2 hybridization. temperature independent CD3COOH results, 58± η ≤ 0.1, indicate rapid hindered rotation CD3 group, correlation time...

Room-temperature visible luminescence from Pr3+ ions embedded in germaniumsulfide glass hosts is reported along with edge these hosts. The important role of energy transfer processes between the host and Pr demonstrated experimentally through dependencies photoluminescence on excitation wavelength, temperature, polarization.