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Related Defects (relate + defect)
Selected AbstractsEvidence of a stoichiometry-related compensation in undoped high-resistivity CdTe crystalsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2004A. Zappettini Abstract Nominally undoped CdTe crystals are grown by both vapour phase and Bridgman technique. The stoichiometry of the feed charge was adjusted in order to obtain n-type, p-type and high resistivity crystals. The stoichiometry of CdTe samples is studied by means of a detailed analysis of the temperature dependence of the equilibrium partial pressures of Cd and Te2 vapours. A strong evidence of a correlation of the stoichiometry and the resistivity of the samples has been found. This suggests that a stoichiometry related defect plays an important role in the compensation mechanism of the nominally undoped crystals. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Acceptor compensation by dislocations related defects in boron doped homoepitaxial diamond films from cathodoluminescence and Schottky diodes current voltage characteristicsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2006P. Muret Abstract This document shows that new electrically active defects can develop in the homoepitaxial layer grown on Ib diamond substrates, related to the increase of the dislocation density. Deep centres, which are able to compensate the boron acceptors, specially when the growth process allows boron incorporation below 1015 cm,3 like achieved in the samples, are identified after heating in an inert gas ambient both from photo-induced current transient spectroscopy (PICTS) and changes in Schottky diode current,voltage characteristics. Cathodoluminescence spectra are used to monitor the bands and excitonic lines, some of them being specific of dislocations. A correlation is demonstrated between the onset of properties characteristic of a compensated semiconductor and the increase of signals associated to dislocations in cathodoluminescence spectra. These modifications are thermally driven only when the samples are laid on a heating holder immerged in an inert gas, suggesting that a temperature gradient induced an additional stress which finally led to plastic relaxation of the tensile strain in the homoepitaxial layer by an increase of the dislocation density. New deep centres being simultaneously created in this degradation process, the problem of overcoming the onset of these defects for implementing high voltage devices is discussed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Observation of Zn vacancies in ZnO grown by chemical vapor transportPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2006F. Tuomisto Abstract We have used positron annihilation spectroscopy to study the vacancy defects in ZnO crystals grown by both the conventional and contactless chemical vapor transport (CVT and CCVT). Our results show that Zn vacancies or Zn vacancy related defects are present in as-grown ZnO, irrespective of the growth method. Zn vacancies are observed in CVT-grown undoped ZnO and (Zn,Mn)O. The Zn vacancies present in undoped CCVT-ZnO are the dominant negatively charged point defect in the material. Doping the material with As introduces also Zn vacancy-related defect complexes with larger open volume. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Positron annihilation spectroscopic study of hydrothermal grown n-type zinc oxide single crystalPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2007C. W. Hui Abstract Positron lifetime and coincidence Doppler broadening spectroscopic (CDBS) measurements were carried out to study the defects in two hydrothermal (HT) grown ZnO single crystal samples (HT1 and HT2) obtained from two companies. Single component model could offer good fittings to the room temperature spectra of HT1 and HT2, with the positron lifetimes equal to 199 ps and 181 ps respectively. These two lifetime components were associated with saturated positron trapping into two VZn -related defects with different microstructures. The positron lifetimes of HT1 was found to be temperature independent. For the HT2 sample, the positron lifetime remained unchanged with T > 200 K and decreased with decreasing temperature as T<200K. This could be explained by the presence of an additional positron trap having similar electronic environment to that of the delocalized state and competing in trapping positrons with the 181 ps component at low temperatures. Positron-electron autocorrelation function, which was the fingerprint of the annihilation site, was extracted from the CDBS spectrum. The obtained autocorrelation functions of HT1 and HT2 at room temperature, and HT2 at 50 K had features consistent with the above postulates that the 181 ps and the 199 ps components had distinct microstructures and the low temperature positron trap existed in HT2. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Deep electron states in indium-doped Cd0.93Mn0.07Te DLTS studyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2006A. Hajdusianek Abstract Electron traps in indium doped Cd0.93Mn0.07Te were studied with Deep Level Transient Spectroscopy. Five electron traps were found (labeled as E1 - E5). Energy levels ET of related defects are equal to ET 1 = 0.09 eV, ET 2 = 0.12 eV, ET 3 = 0.18 eV, ET 4 = 0.56 eV and ET 5 = 0.65 eV. Three of them (E1, E2, E3 ) are related to the defects with thermally activated capture cross section. Electric field enhanced electron emission from the trap E4 was observed and described in the terms of the Poole-Frenkel - mechanism. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Stoichiometry related defects in CdTe crystalsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2004F. Bissoli Abstract In this work, we report on the structural analyses of undoped CdTe samples grown by the vapor phase and the Bridgman methods. Different techniques were used for determining the structural defects: wet etching, high resolution X-ray diffraction, double crystal X-ray topography and monochromatic SEM-cathodoluminescence mapping. The density and the nature of the structural defects were found to be correlated to the stoichiometry of the samples, as determined by a detailed analysis of the temperature dependence of the partial pressure of the vapors in equilibrium with the solid. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The analysis on the origin of high resistivity in Cl-doped polycrystalline CdZnTe thick filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2004K. H. Kim Abstract Polycrystalline CdZnTe thick films were grown by thermal evaporation method using CdZnTe and CdZnTe:Cl source. Non-doped CdZnTe thick films have Te-rich stoichiometry having resistivity 3.3 × 109 ,cm. The Cl-doped CdZnTe thick films have 1.2 × 1010 ,cm in resistivity. To evaluate the role of Cl in the increasement of the resistivity, the density of localized states were calculated from the analysis of transient TOF (time of flight)current. From the comparison of Cl-doped CZT thick films with non-doped and O2 annealed CdZnTe thick films, we have found that Cl doping is related to the formation of states at EV + 0.75 eV region and oxygen reduces grain boundary related defects through formation TeO2 or CdTeO3. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||