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Electrical and Computer Engineering

Old Dominion University

Electrical & Computer Engineering Faculty Publications

2001

Articles 1 - 4 of 4

Full-Text Articles in Physical Sciences and Mathematics

Boron-Doped Homoepitaxial Diamond (100) Film Investigated By Scanning Tunneling Microscopy, Bing Xiao, Weihai Fu, Sacharia Albin, Jason Moulton, John Cooper Jan 2001

Boron-Doped Homoepitaxial Diamond (100) Film Investigated By Scanning Tunneling Microscopy, Bing Xiao, Weihai Fu, Sacharia Albin, Jason Moulton, John Cooper

Electrical & Computer Engineering Faculty Publications

Conducting epitaxial diamond films of high quality are essential for many diamond studies and diamond electronic device fabrication. We have grown boron-doped epitaxial diamond films on type Ila natural diamond (100) substrates by microwave plasma chemical vapor deposition. A gas mixture of H2/CH4 was used. Boron doping was done by placing solid sources of pure boron in the microwave plasma. Homoepitaxial films with atomic smoothness were achieved under the following growth conditions: substrate temperature 900 °C, gas pressure 40 Torr, and gas flow rates of H2/CH4 = 900/7.2 seem. The growth rate was 0.87 …

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Electron Cyclotron Resonance Heating In Spherical Plasmas: O-X-Ebw Mode Conversion In Mast, Josef Preinhaelter, M. A. Irzak, Linda L. Vahala, George Vahala Jan 2001

Electron Cyclotron Resonance Heating In Spherical Plasmas: O-X-Ebw Mode Conversion In Mast, Josef Preinhaelter, M. A. Irzak, Linda L. Vahala, George Vahala

Electrical & Computer Engineering Faculty Publications

Using a full wave solution, the O-X-EBW mode conversion is examined for density and magnetic profiles in MAST. The effects of magnetic shear and the sharp density pedestal for H-mode operation are considered with an eye to understanding both electron cyclotron emission (ECE) and electron cyclotron resonance heating (ECRH).

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Time-Resolved Structural Study Of Low-Index Surfaces Of Germanium Near Its Bulk Melting Temperature, Xinglin Zeng, H. E. Elsayed-Ali Jan 2001

Time-Resolved Structural Study Of Low-Index Surfaces Of Germanium Near Its Bulk Melting Temperature, Xinglin Zeng, H. E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

The structure of the low-index surfaces of germanium near its bulk melting temperature is investigated using 100-ps time-resolved reflection high-energy electron diffraction. The surface is heated by 100-ps laser pulses while a synchronized electron beam probes the structure. Ge(111)was observed to remain in its incomplete melting structure up to at least Tm + 134 ± 40 K when heated by a 100-ps laser pulse. Both the Ge(100) and Ge(110) surfaces are observed to melt near the bulk melting temperature when heated with 100-ps laser pulses. Because of the low-diffraction intensity-to-background ratio at high temperatures and because of the temperature …

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A New Compensating Element For A Femtosecond Photoelectron Gun, Bao-Liang Qian, Hani E. Elsayed-Ali Jan 2001

A New Compensating Element For A Femtosecond Photoelectron Gun, Bao-Liang Qian, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Design and analysis of a new compensating element for improving the electron pulse front and compressing the pulse duration in a femtosecond photoelectron gun are described. The compensating element is a small metallic cylindrical cavity in which an external voltage is applied in such a way that a special electric field forms and interacts with the electron pulse. This electric field reduces the distances between the faster and slower electrons inside the cavity and efficiently compensates for electron pulse broadening caused by the photoelectron energy spread and space charge effects. Poisson's equation and the equation of motion are solved to …

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