Search

The rotation dynamics of the spin probe TEMPO in glycerol from ESR is compared with the ortho-positronium ( o-Ps ) annihilation from PALS and interpreted using the relaxation dynamics from BDS. Rotation time scale within the slow motion regime exhibits two Arrhenius regions with the characteristic ESR temperature, T X1 τ , close to the characteristic PALS temperature, T b1 L , which is related to the secondary β process above T g . Next, a slow to fast motion regime transition at the characteristic ESR temperature, T c τ , close to the characteristic PALS temperature, T b2 L , followed by non-Arrhenius fast motion regime region is fully coupled with the primary α process.

The analysis of non-equilibrium quasistatic CU curves of MIS capacitors reveales that it is possible to distinguish several groups of states differing by their respective effective capture cross sections. A relation between the demarcation energy that separates states in quasi-equilibrium from those in non-equilibrium at the oxide-semiconductor interface, and the equivalent frequency of the quasistatic CU method, is derived. Using the Berglund integral, the surface potential can be calculated even under non-equilibrium conditions. States in the upper half of the gap are found to have up to three orders higher capture cross section for holes compared to that of states in the lower half of the gap.

Silicon wafers with p-n junctions are contaminated by nickel and the temperature behaviour of the reverse current of these p-n junctions is investigated. Nickel-related deep energy levels are studied by DLTS measurement. The dominant energy level of Ni is at Ev + 0.31 eV. The illumination and annealing sensitivity of this level is also observed. An attempt is made to explain qualitatively this phenomenon. Siliziumscheiben mit p-n-Ubergangen werden mit Nickel dotiert, und die Temperaturabhangigkeit des Sperrstroms an diesen Ubergangen gemessen. Die mit Nickel korrelierten tiefen Niveaus werden mit Kapazitatstransienten-Spektroskopie (DLTS) untersucht. Das dominante Niveau fur Nickel wird bei Ev + 0,31 eV gefunden und erweist sich als beeinflusbar durch Beleuchtung und Temperung. Es wird eine qualitative Deutung dieses Phanomens vorgeschlagen.

C–U and DLTS characteristics are measured of aluminium oxide on GaAs obtained by plasma anodisation at different temperatures, Tox, of the substrate. Hysteresis of the flat-band voltage, injection currents, and Fermi-level pinning are observed. Phonon-assisted tunnelling with subsequent trapping in aluminium oxide is the most probable mechanism of the electron injection. The GaAs–oxide interface quality is better for Tox = 150 °C than for Tox = 30 °C. Es werden die C–U- und DLTS-Charakteristiken von Aluminiumoxid auf GaAs gemessen, das durch Plasmaanodisierung bei verschiedenen Substrat-Temperaturen Tox erhalten wird. Hysterese der Flachbandspannung, Injektionsstrome und Ferminiveaufixierung werden beobachtet. Phononenassistiertes Tunneln mit nachfolgendem Anhaften im Aluminiumoxid stellt den wahrscheinlichsten Mechanismus fur die Elektroneninjektion dar. Die GaAs–Oxid-Grenzflachenqualitat ist fur Tox = 150 °C besser als fur Tox = 30 °C.

Polycarbonate was subjected to long-term stress by transverse bending. Stressed, as well as non-fatigued, samples were irradiated by gamma radiation in evacuated ampoules. The concentration of free radicals was measured by ESR in the course of gradual heating of the samples. It appeared that the free radicals in the samples subjected to long-term stress were more stable than the free radicals in the non-fatigued samples. This suggests that the arrangement of polymer chains changes during fatigue and the free volume in the proximity of radical centres decreases so that the transfer of these centres to adjoining chains is retarded.

The cyclic stress-strain curve of single-slip-oriented single crystals of low-stacking-fault-energy alloy Cu-22%Zn was determined on a large number of specimens. There was an expressive plateau extending from a plastic shear strain amplitude of about 7 × 10−4 to about 7 × 10−3. The plateau shear stress amplitude was 43 MPa.

This paper presents a combined description of the ortho-positronium (o-Ps) response from positron annihilation lifetime spectroscopy (PALS) and viscosity data on bis[m-(m-phenoxy) phenoxyphenyl] ether within the free volume version of the two-order parameter (TOP) model of disordered phase. The quasi-sigmoidal form of the temperature dependence of the o-Ps lifetime, τ3, over a wide temperature interval, can be described by an expression with the distribution function for liquid-like domains 1−F(T) which follows from a phenomenological analysis of the viscosity using the modified Vogel–Fulcher–Tamman–Hesse (MVFTH) equation. This simultaneous description indicates a close connection between the PALS response and the viscosity behavior for the matrix and gives support for the liquid-like and solid-like domain physical picture of all the physical states of the disordered phase.

Metal-oxide-semiconductor structures are fabricated on an n-type GaAs substrate at room temperature by means of plasma anodic oxidation of aluminium films evaporated on the GaAs substrate. Current and charge transient spectroscopies and low frequency C-U measurements are applied to the MOS capacitors. The optimum processing condition for the minimum interface-state-density is found to be related to the properties of the Al film. Three apparent activation energies of the dominant DLTS peak (Ec - 0.5 eV, Ec - 0.67 eV, Ec - 0.72 eV) for three concentrations of donors (1024, 2.7 × 1023, and 1.4 × 1022 m−3) are determined; the differences in the values of the energies can be estimated as a consequence of the Poole-Frenkel effect with an extrapolated value of the true energy Ec - 0.75 eV. From this point of view the observed DLTS peaks are attributed to the same defect, which can be connected with two simultaneous processes in the course of oxidation: (1) with the out migration of Ga atoms through the oxide layer and (ii) with the forming of a high resistivity O-compensated layer between the oxide and the semiconductor. Mittels anodischer Plasmaoxydation von Aluminiumschichten auf GaAs-Substraten werden Metall-Oxid-Halbleiterstrukturen auf einem n-leitenden GaAs-Substrat bei Zimmertemperatur prapariert. Strom- und Ladungstransientenspektroskopie und Niederfrequenz C-U- Messungen werden fur die Untersuchung der MOS-Kondensatoren benutzt. Es wird gefunden, das die optimalen Prozesbedingungen fur minimale Grenzflachenzustandsdichte mit den Eigenschaften der Al-Schicht verknupft sind. Drei auftretende Aktivierungsenergien des dominierenden DLTS-Maximums (Ec - 0,5 eV, Ec - 0,67 eV, Ec - 0,72 eV) fur drei Donatorkonzentrationen (1024, 2.7 × 1023, and 1.4 × 1022 m−3) werden bestimmt, die Differenzen in den Energiewerten lassen sich als Folge des Poole-Frenkel-Effekts berechnen, mit einem extrapolierten Wert der wahren Energie Ec - 0,75 eV. Von diesem Standpunkt aus werden die beobachteten DLTS-Maxima demselben Defekt zugeordnet, der mit zwei simultanen Prozessen im Verlauf der Oxydation verbunden sein kann : 1) mit der Migration von Ga-Atomen durch die Oxidschicht und 2) mit der Bildung einer hochohmigen O-Kompensationsschicht zwischen dem Oxid und dem Halbleiter.

The values of van der Waals radii rW's according to Bondi [1] and Stokes [4] were summarized for the chosen atoms of the first, second and third row of MPT namely H, Li, C, N, O, F, Na, Mg, Si, P, S and Cl. They were used in the study on how an actual rW value depends on the electronic state of a given atom and how the interaction of the atom with environment affects this value. For all mentioned atoms individual functional dependences of rW on the net charge of atom were found taking into account the effect of electronic cloud alone and the interaction with surroundings moreover. The formulae obtained were tested on some examples.