Drain current overshoot transient in polycrystalline silicon transistors: The effect of hole generation mechanism

We have investigated the overshoot effect of switch-on transients of polycrystalline silicon thin-film transistors. The investigation has been performed with devices fabricated on laterally grown polycrystalline silicon films having very long crystal domains. These films were crystallized by excimer-laser annealing and had a thickness in the range of 30-100 nm. The measurement of the switch-on transients reveals that the device transient behavior depends significantly on both temperature and illumination conditions. The temperature dependence, under dark state or under illumination, suggests that the mechanism accountable for the transient behavior of thin-film transistors cannot be attributed only to carrier trapping, but rather to a more complex mechanism involving carrier generation and recombination in the device body. This allows the estimation of the dependence of generation lifetime on the polycrystalline film thickness.