Abstract

Materials with subpicosecond response times allow fabrication of sources for terahertz signal generation such as photomixers, photoswitches and photodetectors operating over an extremely wide frequency band. Material most widely used for these applications is low-temperature-grown GaAs (LTG-GaAs). Control over the response time in LTG-GaAs is achieved by changing the growth and post-growth annealing temperatures, which in turn determine concentration of As-antisite point defects, responsible for the electron and hole trapping. However, LTG-GaAs with subpicosecond response times can only be obtained over a very limited range of technological conditions, besides, epitaxial layers with such short response times cannot be thicker than, approximately, 0.5 μm. The maximum thickness is limited by the internal strains caused by the large amount of excess As in LTG layers.

© 2000 IEEE