The project involves research on intraband (as opposed to interband) processes in semiconductor devices and related research on new device concepts. The research will include electronic and infrared measurements as well as device physics theory and modeling. The research will be oriented toward improved understanding of intraband process in silicon and selectively doped A1GaAs/GaAs and toward concepts which could contribute to the development of (A) ultrafast devices for logic, infrared data transmission, and oscillator applications, (B) new types of infrared detectors and (C) new means of electronic implementation of neural networks. Some of the proposed work is exploratory while other aspects represent a continuation of current research. In accord with our predictions, intraband processes involving tunneling and photoexcitation have been found to have special advantages in terms of electronic switching speed and the ability to tailor infrared detectors for optimal response at particular wavelengths. The research will deal with issues related to picosecond switching and the analogous frequency domain for heterostructure devices. The work will include analysis of corrections to the standard treatment of Tsu-Esaki tunneling as well as electron-electron interactions and heterostructure interface roughness. Infrared detector concepts involving nonlinear effects in extrinsic silicon devices and heterostructures will be developed and effects at impurity band interfaces will be studied.
