Thermally stable, superlattice-enhanced 1.3- mu m InGaAs IMSM photodetectors on GaAs substrates

Dark current, DC responsivity, and high-frequency response data of 1.3- mu m interdigitated metal-semiconductor-metal (IMSM) photodetectors on a thermally stable, superlattice-enhanced InGaAs/GaAs structure are reported. Auger analysis revealed that the superlattice cap layer is capable of inhibiting the out-diffusion of indium to the surface during high-temperature annealing cycle, thus minimizing the degradation of the optical and electrical characteristics of the photodetectors fabricated on this material. The internal quantum efficiency and high-frequency bandwidth of the detectors are over 91% and 14 GHz, respectively. The stability of this IMSM structure to high-temperature annealing offers the potential for fabrication of low-cost, long-wavelength monolithic receivers based oil GaAs MESFET technology.<
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