Enhancement of Light-to-Dark Current Ratio via Coupling Effect for MIS (p) Tunnel Diode Photo Sensors

The current of metal-insulator-semiconductor (MIS) tunnel diodes is dependent on the Schottky barrier height and there are different mechanisms which dominate MIS tunnel currents while MIS tunnel diodes are biased at positive and negative voltages. In this work, coupled current-voltage behaviors were observed in a MIS(p) tunnel diode with a MOS structure coupled nearby (1). It was found that the MIS(p) saturation tunneling current could be controlled by the voltage bias (VG) of the nearby MOS capacitor. While Inchanges, the minority carrier distribution at the fringe of the MIS tunnel diode also changes. As a result, by well-controlling VG, the light to dark current ratio Ilight/Idark can be effectively enhanced. In this study, two intensities of illumination on MIS(p) tunnel diodes of three different oxide thicknesses were displayed. It is shown that under both intensities of illumination, the light to dark current ratio Ilight/Idark are all effectively enhanced by well-controlling VG. It is also found that the maxima of current ratio Ilight/Idark take place at different values of VG for different intensities of illumination. The coupling effect plays an important role in this phenomenon. © The Electrochemical Society.