Voltage-tunable duial-band In(Ga)As quantum-ring infrared photodetector

The ten-period In(Ga)As quantum-ring infrared photodetector (QRIP) prepared by molecular beam epitaxy is investigated. The quantum rings show narrow-sized distributions that are segregated into two groups. The QRIP demonstrates a dual-band operation with response peak shifting from the long wavelength of 9.5 mu m at biases less than 0.6 V to the middle wavelength of 6.8 mu m at biases larger than 0.8 V. The maximum peak responsivity at 20 K is 422 mA/W at 1.2-V bias.