Responsivity and noise performance of InGaAs/InP quantum well infrared photodetectors

Dark current nose measurements were carried out between 10 and 104 Hz at T equals 80K on two InGaAs/InP quantum well IR photo detectors (QWIPs) designed for 8 micrometers IR detection. Using the measured noise data, we have calculated the thermal generation rate, bias-dependent gain, electron trapping probability, and electron diffusion length. The calculated thermal generation rate is similar to AlGaAs/GaAs QWIPs with similar peak wavelengths, but the gain is 50 X larger, indicating improved transport and carrier lifetime are obtained in the binary InP barriers. As a result, a large responsivity of 7.5 A/W at 5V bias and detectivity of 5 X 10$_11) cm (root) Hz/W at 1.2 V bias were measured for the InGaAs/InP QWIPs at T equals 80K.