Kelvin-probe surface voltage mapping, SVM, on epitaxial SiC, charged with corona into deep depletion, reveals SV defects manifested as spots with decreased surface voltage. For 150μm thick epi-layer, SV defects coincide with low carrier lifetime spots revealed by microwave detected photoconductance decay, μPCD. In the photoluminescence image, these defects are seen as triangular dark spots, described in literature as stacking-fault related triangular defects. For thin epi-layers (2.2μm), defects are visible only in SVM. In this case, high resolution SVM performed with Kelvin Force Microscopy identifies a triangular defect shape. Two mechanisms are proposed, accounting for SV defects. For high intensity defects exhibiting large magnitude fast decreasing voltage, the probable mechanism is defect related leakage; causing neutralization of corona surface ions. Low intensity defects can be explained considering deep level emission. The latter mechanism has been investigated using SV transient and spectral analysis analogous to isothermal DLTS and Laplace DLTS.
Experimental results for a new method of measuring the minority carrier lifetime as a process control tool to determine trace metal contamination following wafering and epitaxial growth of silicon in a production environment are reported. In this new method the minority carrier lifetime is measured by microwave photoconductive decay (µ-PCD) while charging the surface silicon oxide with a corona charge. We have named the method Charge-PCD. Results are given comparing various qualities of the surface oxides prepared by low temperature methods coupled with various corona charging recipes in order to determine the optimum process and limitations of the new method.
A szerzôk egy ritka, krónikus lefolyású, szervspecifikus autoimmun kórkép, a pemphigus vulgaris egy esetét ismertetik. A beteget gyógyszerelhagyást követôen fellángoló, kiterjedt, részben bullosus, részben erodált bôrtünetek, romló fizikális status miatt hospitalizálták. Szisztémás kortikoszteroid és azathioprin adása ellenére bôrstátuszában további progressziót, illetve szövôdményként szisztémás infekciót észleltek. A romló vérkép és májfunkciós eltérések tovább nehezítették a gyógyszeres kezelés fenntartását. Human immunglobulin parenterális alkalmazását követôen a betegség kontrollálhatóvá vált. Jelenleg egy éve tartó nyomonkövetés során recidivát nem észleltek. A szerzôk az eseten keresztül a kórkép egyre pontosabban ismert immunológiai hátterére, valamint az egyre bôvülô terápiás lehetôségekre szeretnék a figyelmet felhívni.
The 50-year neuropathology documentation reflects changes in the occurrence of diseases, and it calls attention to those disorders which can be prevented or treated today, but may represent diagnostic challenges.
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