Near-infrared photodetection in n-type nanocrystalline FeSi2/p-type Si heterojunctions.

n-Type nanocrystalline (NC) FeSi2/p-type Si heterojunctions, which were prepared by pulsed laser deposition, were evaluated as a near infrared photodiode. The built-in potential was estimated to be approximately 1.1 eV from the capacitance-voltage measurement. These junctions showed a rectifying behavior accompanied by a large leakage current. The near infrared light detection performance was evaluated using a 1.33 microm laser in the temperature range of 77-300 K. At a reverse bias of -5 V, the detectivity was 5.5 x 10(7) cm Hz1/2 W(-1) at 300 K and it was dramatically enhanced to be 8.0 x 10(10) cm Hz1/2 W(-1) at 77 K. It was demonstrated that NC-FeSi2 is a new potential material applicable to NIR photodetectors operating at low temperatures.