Fig. 1. Structure of the detector. The absorption layer consists of 500 nm intrinsic In0.53Ga0.47As and the DBS consists of 1.4 nm AlAs, 6 nm In0.53Ga0.47As and 1.4 nm AlAs. A 30 nm In0.53Ga0.47As p-charge layer with doping concentration of 1×1018  cm−3 is added to modulate the band energy of the detector.

Fig. 2. Simulated band energy variation of the detector after adding the p-charge layer. The bias voltage of the detector is set at 0.2 V.

Fig. 3. Dark current lowering mechanism. For clarity, the thickness of each layer is not proportional to their real value.

Fig. 4. Tested dark current density of the detectors. The diameter of the circle mesa is 25 μm.

Fig. 5. Photo-response of the detector. The temperature of the blackbody is set at 1073 K and the emergent light is filtered by a light filter with a central wavelength around 1500 nm and a bandwidth of 1000 nm. The detector is placed in front of the blackbody with a linear distance of 12 cm.

Fig. 6. Responsivity of the detector.

Fig. 7. Time-resolved photocurrent of the detector at room temperature. The frequency of the laser pulses is 5 kHz and the bias voltage of the detector is 0.29 V.

Fig. 8. RMS signal voltage and RMS noise voltage of the detector. The incident power on the photosensitive area of the detector is 50 pW and the frequency of the laser pulses is 5 kHz.