Origin of the Ultrafast Response of the Lateral Photovoltaic Effect in Amorphous MoS/Si Junctions.

The lateral photovoltaic (LPV) effect has attracted much attention for a long time because of its application in position-sensitive detectors (PSD). Here, we report the ultrafast response of the LPV in amorphous MoS/Si (a-MoS/Si) junctions prepared by the pulsed laser deposition (PLD) technique. Different orientations of the built-in field and the breakover voltages are observed for a-MoS films deposited on p- and n-type Si wafers, resulting in the induction of positive and negative voltages in the a-MoS/n-Si and a-MoS/p-Si junctions upon laser illumination, respectively. The dependence of the LPV on the position of the illumination shows very high sensitivity (183 mV mm) and good linearity. The optical relaxation time of LPV with a positive voltage was about 5.8 μs in a-MoS/n-Si junction, whereas the optical relaxation time of LPV with a negative voltage was about 2.1 μs in a-MoS/p-Si junction. Our results clearly suggested that the inversion layer at the a-MoS/Si interface made a good contribution to the ultrafast response of the LPV in a-MoS/Si junctions. The large positional sensitivity and ultrafast relaxation of LPV may promise the a-MoS/Si junction's applications in fast position-sensitive detectors.