Near-infrared photodetection of β-FeSi2/Si heterojunction photodiodes at low temperatures

n-type β-FeSi2/p-type Si heterojunction photodiodes were fabricated by facing-targets direct-current sputtering, and their near-infrared photodetection properties were studied in the temperature range of 50–300 K. At 300 K, devices biased at −5 V exhibited a current responsivity of 16.6 mA/W. The measured specific detectivity was remarkably improved from 3.5 × 109 to 1.4 × 1011 cmHz1/2/W as the devices were cooled from 300 K down to 50 K. This improvement is mainly attributable to distinguished suppression in heterojunction leakage current at low temperatures. The obtained results indicate that β-FeSi2/Si heterojunctions offer high potential to be employed as near-infrared photodetectors that are compatible with the current Si technology.