OPTOELECTRONIC APPLICATIONS OF LTMBE III-V MATERIALS

A review of the application of semiconductor layers grown at low substrate temperatures to ultrafast optoelectronics is presented. The films, grown by molecular beam epitaxy primarily around 200 degrees C and subsequently annealed, are demonstrated to have high resistivity, high mobility, an ultrashort carrier lifetime, and a high dielectric breakdown. This combination of properties makes the low-temperature-grown materials 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 thickness, and optical wavelength, are considered. Examples of low-temperature-grown semiconductor optoelectronic devices, including ultra-high-bandwidth photoconductive detectors, high-sensitivity, high-bandwidth MSM photodetectors, and optical temporal analyzers are demonstrated. While the discussion concentrates on low-temperatures-grown GaAs, the lattice-mismatched ternary compound InxGal-xAs/GaAs is also considered in the context of detection of the longer wavelengths used in optical communications.