OPTOELECTRONIC APPLICATIONS OF LTMBE III-V MATERIALS

A review of the application of semiconductor layers grown at low subst rate temperatures to ultrafast optoelectronics is presented. The films , grown by molecular beam epitaxy primarily around 200 degrees C and s ubsequently annealed, are demonstrated to have high resistivity, high mobility, an ultrashort carrier lifetime, and a high dielectric breakd own. This combination of properties makes the low-temperature-grown ma terials perfectly suited for use in high-speed optoelectronic devices. A number of issues which influence the application of these materials , such as growth temperature, use of an annealing process, layer thick ness, and optical wavelength, are considered. Examples of low-temperat ure-grown semiconductor optoelectronic devices, including ultra-high-b andwidth photoconductive detectors, high-sensitivity, high-bandwidth M SM photodetectors, and optical temporal analyzers are demonstrated. Wh ile the discussion concentrates on low-temperatures-grown GaAs, the la ttice-mismatched ternary compound InxGal-xAs/GaAs is also considered i n the context of detection of the longer wavelengths used in optical c ommunications.