High responsivity short-wavelength dual-band photodetector based on AlInAsSb digital alloy

We have demonstrated a monolithic and optically-aligned short-wavelength (SW) dual-band photodetector with Al0.6In0.4AsSb/Al0.3In0.7AsSb (APD/SW) back-to-back p-i-n/n-i-p structures on GaSb substrate. The three-terminal architecture was used to ensure complete electrical isolation of the two sub-detectors at operating bias and to enable simultaneous detection and output of the APD signal and SW signal. Low optical crosstalk (<-10 dB) between the two sub-detectors is achieved for the 1095-1185 nm range. At 300K, the APD sub-detector has a unity gain responsivity of 0.237A/W, at -1 V, and a specific detectivity of 2.64 ×1011 cm·Hz1/2/W at 1035 nm. At a reverse bias voltage of 40.8V, the APD sub-detector achieves a maximum responsivity is 3.594 A/W of 1064 nm and 2.098 A/W of 635 nm. Meanwhile, the SW sub-detector under -1V has a responsivity of 0.424 A/W, and a specific detectivity of 2.78 ×1010 cm·Hz1/2/W at 1723 nm.