Light Detection and Carrier Transportation Mechanism in p-Type Si/n-Type Nanocrystalline FeSi2 Heterojunctions Produced via Radio-Frequency Magnetron Sputtering

Abstract

In the current research, p-type Si/n-type nanocrystalline FeSi2 heterojunctions were fabricated at room temperature with an argon pressure of 2.66×10−1 Pa by means of the utilization of a radiofrequency magnetron sputtering technique. These heterojunctions were studied for the carrier transportation mechanism and near-infrared (NIR) light detection at various temperatures ranging from 300 K down to 150 K. At 300 K, the fabricated heterojunctions displayed a typical rectifying action together with substantial leakage current. At 150 K, the leakage current was clearly reduced by greater than four orders of magnitude. The value of the ideality factor (n) at 300 K was computed to be 1.87 and this was nearly constant under temperatures ranging from 300 down to 260 K. This implies that a recombination process was predominant. At temperatures lower than 250 K, the value of n was found to be more than 2. These results demonstrated that the carrier transportation mechanism was governed by a tunnelling process. A weak response for the irradiation of NIR light was observed at 300 K. At 150 K, the ratio of the photocurrent to the dark current evidently increased by more than two orders of magnitude. The detectivity at 150 K was 4.84×1010 cm Hz1/2 W−1 at zero bias voltage, which was clearly improved as compared to that at 300 K.