Growth and Electrical and Far-Infrared Properties of Wide Electron Wells in Semiconductors.

摘要

The thrust of the research carried out under this grant has been the development and study of wide, specially shaped graded quantum wells for electrons in semiconductors, as synthesized by high-precision epitaxial growth. In basic characterization of the wide wells, fundamental measurements of charge density, energy levels, and electron motions in the wells were pursued. The achievement of high-Q solid state electron resonators at Terahertz frequencies in the wide wells was stressed. Highly resonant cavities with electron scattering times nearly two orders of magnitude larger than for electrons in high-purity uniformly doped wells of comparable electron concentration have been grown. Structures were also achieved in which the resonant frequency of the electrons could be changed by application of a potential to a control electrode. Modification of the parabolic potential by superposition of periodic potentials and the extension of the parabolic well concept to remotely doped hole wells were also emphasized.