1,721,005 research outputs found
Determination of generation lifetime in trap-rich and layered semiconductors by Metal-Oxide-Semiconductor (MOS) measurements
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Comparison of lifetime measurements from the Zerbst and the dispersion techniques
No full textThe admittance of metal oxide semiconductor (MOS) diode after switching from inversion to deep depletion is calculated. Special attention is given to the final stationary state in inversion conditions. For this state the relaxation equations must be modified because the usually assumed large signal carrier deficits are not valid. The results of these dispersion measurements are compared with the conventional Zerbst technique. Good agreement is obtained. The dispersion technique is a valuable tool for determining very short lifetimes
THERMAL DONOR FORMATION IN OXYGEN ENRICHED HIGH RESISTIVE FLOAT-ZONE SILICON RADIATION DETECTOR SUBSTRATES
No full textAdmittance measurements on a-Si/c-Si heterojunction solar cells
No full textHydrogenated amorphous silicon/ crystalline silicon (a- Si: H/ c- Si) solar cells with areas of 1 x 1 cm are produced by deposition of a- Si: H and indium- tin- oxide (ITO) on 3- in. wafers. Three types of samples have been prepared for admittance measurements, differing in the way how the effective area is defined. The measurement geometry is either defined by cutting, by etching the ITO layer outside the 1 cm(2) active area, or by etching the ITO and the a- Si: H outside the active area. Admittance measurements reveal that the lateral conductivity of the ITO is high enough up to a frequency of 1 MHz to ensure a lateral equipotential surface. A simple equivalent network consisting of a parallel resistor- capacitor branch in series to a second resistor controls the cut sample. For the sample with just ITO layer etching, the effects of a lateral channel due to the a- Si: H layer have to be included. The finite dimensions of the sample modify the low- pass character of the channel. The sample with ITO and a- Si: H layer etching delivers the best measurement conditions. In all three cases the dispersion allows the surface doping level of the substrate to be extracted from the CV characteristics measured at 1 MH
NUMERICAL SIMULATION OF TIME RESOLVED CHARGE TRANSPORT IN SEMICONDUCTOR STRUCTURES FOR ELECTRONIC DEVICES.
No full textExcess charge carrier transport and relaxation in semiconductor layered structures have been numerically simulated by a finite-difference method. The standard mathematical model of charge transport in semiconductors has been used, consisting of two continuity, two diffusion and two drift equations and a Poisson equation involving electron, hole concentrations and potential. The relaxation process is described by means of Shockley-Read-Hall recombination statistics. The equations of the model are solved in a one-dimensional space domain and the time domain. The simulation program can be used to deduce semiconductor parameters like bulk lifetime, surface recombination velocity, diffusion coefficients and mobilities of electrons and holes from measurements of photoconductance decay.
A technique for a direct measurement of the recombination velocity at a wafer's surface or interface is presented. It is based on the measurement of the initial photoconductance decay after laser pulse excitation of excess charge carriers in a very shallow layer at the surface or interface. Under conditions to be fulfilled for a correct measurement, the initial decay process is dominated by recombination at the surface and the decay of the measured curve depends almost exclusively on the surface recombination velocity. In this case the simulation program is necessary to interpret the measurement data
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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