Response of Elementary Semiconducting Structures to a Terahertz Electric Field
With a bulk plasma frequency in the terahertz range, extrinsic semiconductors may be employed to form composites with tailored dispersion characteristics for fabrication of passive components in the terahertz band. Computations have been performed to study the polarization process in nanoscale semiconducting plates and spheres, employing a transport formulation to account for space-charge effects. Results reveal a frequency dependent dipole moment that is influenced by the carrier density when it reaches 1016 cm-3 and size dependence as it approaches the characteristic length in field screening by the space charge.
Quasi-static analysis is applicable when the carrier concentration is below 1020 cm-3. Beyond this, full-wave solution is needed to provide a realistic description of the charge-wave interaction within a conductive particle. To obtain higher contrast in dispersion effects resulting from the polarization of mobile charges, a material with lower intrinsic permittivity is preferred for developing composites with dispersion properties that are adjustable by composition variation and fabrication processes.
Thomas T. Y. Wong received the B.Sc. (Eng.) degree from the University of Hong Kong, and the M.S. and Ph.D. degrees from Northwestern University, all degrees being in electrical engineering. In 1981 he joined the faculty of the Illinois Institute of Technology, where he is now a professor in the Department of Electrical and Computer Engineering. Besides conducting research in the Microwave and RF Laboratory at IIT, he collaborates in research in applied electromagnetics at the nearby national laboratories.
His administrative responsibilities included appointments as the ECE graduate program director, the chair of the faculty council, and the chairman of the ECE Department. He is the author of Fundamentals of Distributed Amplification (Artech, 1993), coauthor of Electromagnetic Fields and Waves (Higher Education Press, 2006) and has several patents in the areas of microwave electronics and wireless system design.