High-Speed Insb Photodetectors On Gaas For Mid-Ir Applications

We report p-i-n type InSb-based high-speed photodetectors grown on GaAs substrate. Electrical and optical properties of photodetectors with active areas ranging from 7.06 x 10(-6) cm(2) to 2.25 x 10(-4) cm(2) measured at 77 K and room temperature. Detectors had high zero-bias differential resistances, and the differential resistance area product was 4.5 Omega cm(2). At 77 K, spectral measurements yielded high responsivity between 3 and 5 mum with the cutoff wavelength of 5.33 mum. The maximum responsivity for 80-mum diameter detectors was 1.00x10(5) V/W at 4.35 mum while the detectivity was 3.41x10(9) cm Hz(1/2) /W. High-speed measurements were done at room temperature. An optical parametric oscillator was used to generate picosecond full-width at half-maximum pulses at 2.5 mum with the pump at 780 nm. 30-mum diameter photodetectors yielded 3-dB bandwidth of 8.5 GHz at 2.5 V bias.