51,365 research outputs found
Water Engineering 11-Water and Wastewater Treatment : WENG 2/2
No full textExamination on Water Engineering 11-Water and Wastewater Treatment : WENG 2/2, Dec 201
Ultra-sensitive lithium niobate thermometer based on a dual-resonant whispering-gallery-mode cavity
Full text linkAbstract not availableWenle Weng, Philip S. Light and Andre N. Luite
Chang T'ien Tse : Sino-Portuguese Trade from 1514 to 1644
No full textCheong Weng Eang. Chang T'ien Tse : Sino-Portuguese Trade from 1514 to 1644. In: Revue française d'histoire d'outre-mer, tome 61, n°224, 3e trimestre 1974. p. 500
Relational Bonds and Customer’s Trust and Commitment - A Study on the Moderating Effects of Web Site Usage
No full text
p-n Junction Formation in i-Ge Crystal by Laser Radiation
No full textP-n junction is the main component of many semiconductor devices. Thermodiffusion, ion implantation and molecular beam epitaxy are only a few methods to form a p-n junction. The main drawback for these methods is high cost per p-n junction since the equipment for these methods is expensive. A possibility of p-n junction formation by laser radiation was shown in several p- and n-type semiconductors: p-Si[1,2], p-CdTe[3], p-InSb[4,5], p-InAs[6], p-PbSe[7] and p-Ge[8] due to inversion of conductivity type. Unfortunately, the mechanism of p-n junction formation by laser radiation is not clear until now.
In the present research rectification effect of current-voltage characteristic in pure intrinsic Ge crystal after irradiation by Nd:YAG laser was observed. The effect is characterised by threshold intensity of the laser radiation. Increase of rectification ratio of current-voltage characteristics and barrier height with intensity of the laser radiation, energy of laser radiation quanta and number of pulses was observed in this experiment. The mechanism of this phenomenon is explained by generation and redistribution of intrinsic point defects in temperature gradient field, which causes strongly absorbed laser radiation. The redistribution of defects takes place because interstitial atoms drift towards the irradiated surface, but vacancies drift in the opposite direction – in the bulk of semiconductor according to Thermogradient effect. Since interstitials in Ge crystal are of n-type and vacancies are known to be of p-type, a p-n junction is formed.
[1] Y. Mada et al. Appl. Phys. Lett., 48, pp. 1205 (1986).
[2] J. Blums et al. Physics Status Solidi (a), K91, (1995).
[3] A. Medvid’ et al., Radiat. Meas., 33, 725 (2001).
[4] I. Fujisawa, Jap., J. Appl. Phys, 19, 2137 (1980).
[5] A. Medvid‘ et al. Vacuum, 51, 245 (1998).
[6] L. Kurbatov et al. Reports of Acad. Sc.USSR, 268, 594 (1983)
[7] K.D. Tovstyuk et al. Ukrainian Journal of Physics, 21, 1918 (1984).
[8] S.G. Kiyak et al. Physics and Technics of Semiconductors, 18, 1958 (1984).
Acknowledgments.
The author gratefully acknowledges financial support in part by Europe Project in the Framework of MATERA+ project, European Regional Development Fund within the project “Sol-gel and laser technologies for the development of nanostructures and barrier structures”, the ESF Projects No. 1DP/1.1.1.2.0/09/ APIA/VIAA/142 and «Support for the implementation of doctoral studies at Riga Technical University»
Experimental investigation into the effect of substrate clamping on the piezoelectric behaviour of thick-film PZT elements
No full textThis paper details an experimental investigation of the clamping effect associated with thick-film piezoelectric elements printed on a substrate. The clamping effect reduces the measured piezoelectric coefficient, d33, of the film. This reduction is due to the influence of the d31 component in the film when a deformation of the structure occurs, by either the direct or indirect piezoelectric effect. Theoretical analysis shows a reduction in the measured d33 of 62%, i.e. a standard bulk lead zirconate titanate (PZT)-5H sample with a manufacturer specified d33 of 593pC/N would fall to 227.8pC/N. To confirm this effect, the d33 coefficients of five thin bulk PZT-5H samples of 220µm thickness were measured before and after their attachment to a metallized 96% alumina substrate. The experimental results show a reduction in d33 of 74% from 529pC/N to 139pC/N. The theoretical analysis was then applied to existing University of Southampton thick-film devices. It is estimated that the measured d33 value of 131pC/N of the thick-film devices is the equivalent of an unconstrained d33 of 345pC/N
- …
