66 research outputs found
Electron microscope images of defects in crystal lattices
No full textSIGLEAvailable from British Library Document Supply Centre- DSC:D66817/86 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
A method for rigid body expansion measurement in the presence of secondary grain boundary dislocations applied to a SrTiO3 grain boundary
No full textDISLOCATIONS IN SEMICONDUCTORS AS STUDIED BY WEAK-BEAM ELECTRON-MICROSCOPY
No full textOn discute la configuration des dislocations observées dans les semi-conducteurs à l'aide de la technique du faisceau faible en microscopie électronique. La dissociation de ces dislocations est bien avérée. Plusieurs problèmes relatifs à la géométrie de ces dislocations sont bien résolus. Par contre les observations révèlent l'existence de nouveaux problèmes géométriques non encore résolus.The configuration of dislocations in semiconductors as revealed by the weak-beam method of electron microscopy is discussed. The dissociation of these dislocations has been clearly established, but while many earlier questions concerning the dislocation geometries have been resolved, new dislocation geometries have been revealed which are as yet unexplained
Demonstration of 2 x 2 heterodyne receiver array at 1.4THz using HEB mixers and Fourier phase grating LO
No full textThis master thesis demonstrates the realization of a 2×2 heterodyne receiver array at 1.4 THz based on superconducting hot electron bolometer (HEB) mixers and a Fourier phase grating local oscillator (LO). This is the first time to build a heterodyne receiver array based on these two techniques at such a high frequency. The theoretical knowledge of two key components in this receiver array, HEB mixer and Fourier phase grating, have been elaborated in this thesis. The Fourier phase grating is further used in designing LO optical path to fit the array configuration. We also characterize the overall performances of this receiver array, including the required optimal pumped LO power, noise temperature, IF bandwidth and stability. Based on the fact that the phase grating duplicate the incoming single LO source, we suggest an idea of stabilizing two pixels using one stabilization circuit for the first time. This can reduce the complexity in designing large array. This 1.4 THz receiver array can also be served as a prototype for developing future 4.7 THz array in GUSSTO project, which is proposed to flight by NASA.TelecommunicationMicroelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc
Professor D.J.H. Cockayne FRS: An appreciation in honour of his retirement in September 2009
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