Bulk InAsSb-based Upside-Down Pcbn Photodetectors with Greater Than 5 Μm Cut-off Wavelength

The InAsSb-based photodetectors covering the whole mid-infrared wavelength at 150 K have been modeled, successfully fabricated, and characterized. In this work, we increased the Sb composition in InAs1−xSbx to extend the cut-off wavelength; simultaneously, the novel upside-down structure was adopted to decrease the dark current to ensure good performance of the device at high operating temperature. The growth sequence of the upside-down InAs0.81Sb0.19/AlAsSb material system was reversed to the conventional nBn structure, and the AlSb/AlAs0.08Sb0.92 electron compound barrier was grown before the InAs0.81Sb0.19 active layer. At 150 K and 0.8 V forward bias, the fabricated photodetector demonstrates a dark current density around 3.46 × 10−4 A/cm2, a peak responsivity up to 1.89 A/W, and a quantum efficiency up to 56% at 4.2 µm, corresponding to 1.23 × 1011 cm Hz1/2/W detectivity.