| This dissertation presents work done on materials and novel devices made with MBE-grown Er-doped III-V semiconductors for optoelectronic applications. Optically-excited Er;Exhaustive photoluminescence (PL) characterization was conducted on the entire gamut of As-based III-V semiconductors doped with Er, on bulk as well as quantum-well structures. We did not observe any Er-related PL emission at 1.54 ;Intensive structural characterization (Double-crystal X-ray and TEM) performed by us on GaAs:Er epilayers indicates the presence of high-density nanometer-sized ErAs precipitates in MBE-grown GaAs:Er. These metallic nanoprecipitates probably form internal Schottky barriers within the GaAs matrix, which give rise to Shockley-Read-Hall recombination centers, thus accounting for both the high resistivities and the ultrashort carrier lifetimes.;Optoelectronic devices fabricated included novel tunable (in terms of speed and responsivity) high-speed metal-semiconductor-metal (MSM) photodiodes made with GaAs:Er. Pseudomorphic AlGaAs/InGaAs MODFETs (for high-speed MSM-FET monolithically integrated optical photoreceivers) were also fabricated using a GaAs:Er buffer layer which substantially reduced backgating effects in these devices. |
