Leakage Currents in P-Channel Accumulation Mode Tft's

ABSTRACTWe have fabricated accumulation mode MOSFETS in poly-silicon thin films and studied the effect of passivation of the leakage currents in these devices. We have used C-V measurements ot determine the effective doping concentration and depletion layer widths in the passivated and unpassivated devices. We find that passivation reduces the effective doping concentration and therefore increases the depletion layer width. Although this change in effective doping concentration is small (less thean a factor of 2), the increase in depletion layer width is sufficient to pinch off the passivated device but not the unpassivated one. This leads to the dramatic reduction in leakage currents after passivation.