Experimental observation of conductance transients in Al/SiNx:H/Si metal-insulator-semiconductor structures

Room temperature conductance transients in the SiNx:H/Si interface are reported. Silicon nitride thin films were directly deposited on silicon by the low temperature electron-cyclotron-resonance plasma method. The shape of the conductance transients varies with the frequency at which they are obtained. This behavior is explained in terms of a disorder-induced gap-state continuum model for the interfacial defects. A perfect agreement between experiment and theory is obtained proving the validity of the model. (C) 1997 American Institute of Physics

Deep levels in p(+)-n junctions fabricated by rapid thermal annealing of Mg or Mg/P implanted InP

In this work, we investigate the deep levels present in ion implanted and rapid thermal annealed (RTA) InP p(+)-n junctions. The samples were implanted with magnesium or coimplanted with magnesium and phosphorus. These levels were characterized using deep level transient spectroscopy (DLTS) and capacitance-voltage transient technique (CVTT). Seven majority deep levels located in the upper half of the band gap were detected in the junctions by using DLTS measurements, four of which (at 0.6, 0.45, 0.425, and 0.2 eV below the conduction band) result from RTA, while the origin of the other three levels (at 0.46, 0.25, and 0.27 eV below the conduction band) can be ascribed to implantation damage. An RTA-induced origin was assigned to a minority deep level at 1.33 eV above the valence band. From CVTT measurements, several characteristics of each trap were derived. Tentative assignments have been proposed for the physical nature of all deep levels

Characterization of the EL2 center in GaAs by optical admittance spectroscopy

We have measured the electron optical capture cross section, σ0n(hν), of EL2 (the most important native center in GaAs) using a new technique which we have recently developed: optical admittance spectroscopy. This is a spectroscopic technique based on the measurement of the capacitance and conductance of a junction under monochromatic light of energy hν. This technique allows the measurement of the spectrum σ0n(hν) of each center located in the band gap. We have measured the electron photoionization cross section of the EL2 center, σ0n(hν), at three different temperatures within a range limited at high temperature by thermal emission and at low temperature by photoquenching (a feature characteristic of EL2 below 140 K). The study of the experimental data reveals that this center has a more complex nature than that of a simple defect. It seems to behave like a family of very close levels corresponding to similar atomic structures and located near the midgap. These results also reveal the existence of a sha..

Presence of antibody to A- and B-transferases in minor incompatible bone marrow transplants

The contribution of the bone marrow to plasma A- or B-transferase activities has been studied in patients who underwent incompatible bone marrow transplantation (BMT). As deduced from major incompatibility (group O recipient/A donor), the contribution of the marrow to these plasma activities was c. 5–10% of the total activity. In cases of minor incompatible transplants (A recipient/O donor), normal plasma activity was present in two patients, while no activity was found in a further two in whom a potent anti-transferase was detected. The antibody inhibited both A- and B-transferase activities to a high titre. The patients in whom this antibody arose exhibited severe graft-versus-host disease.Peer Reviewe