Submillimeter quantum electronics

Tunneling phenomena have been explored in quantum wells consisting of GaAs/GaAlAs (Gallium Arsenide/Aluminum Gallium Arsenide) heterostructure layers that were grown by molecular beam epitaxy. Devices such as detectors and mixers have been fabricated from these quantum wells that showed characteristic tunneling response from DC to 2.5 THz. In addition, the negative differential resistance that was observed was used to demonstrate microwave oscillations up to 20 GHz, both at low temperatures and at room temperature. A variety of other submillimeter experiments are described in the reprints included in the appendices: heterodyning from millimeter wave to optical frequencies using GaAs MESFETs above f sub T, heterodyne radiometry measurements of the 557 GHz water vapor rotational line, development of a submillimeter radiometer using a solid-state local oscillator, and submillimeter astronomical observations carried out at telescope field sites. Also mentioned are persistent photoconductivity observed in quantum wells and a low-IF submillimeter heterodyne receiver to be used in electromagnetic scattering experiments.