AlGaAsSb/InGaAsSb phototransistors for 2-μm remote sensing applications

Two-micron detectors are critical for atmospheric CO2 profiling using the lidar technique. InGaAs and HgCdTe detectors are commercially available for this wavelength but they lack sufficient gain, which limits their detectivity. The characterization results of a novel AlGaAsSb/InGaAsSb phototransistor for 2-μm application are reported. The device was developed by AstroPower, Inc. for NASA Langley Research Center. Spectral response measurements showed the highest responsivity in a 1.9- to 2.1-μm region with a maximum value of 2650 A/W at 2 μm. A 2-μm detectivity of 3.9×10 11 cm Hz 1/2 /W was obtained, which corresponds to noise equivalent power of 4.6×10 –14 W/Hz 1/2 .