Programming and erasing operations of nitride-nitride-oxynitride stacked thin film transistor device

We investigated the programming and erasing operations of low temperature polycrystalline silicon thin film transistors (TFTs) including a nitride-nitride-oxynitride (NNOn) structure for a new nonvolatile memory application. From capacitance-voltage characteristics, we found that high hysteresis performance was induced by the optical energy bandgap and thickness of each functional layer consisting of tunneling, trapping, and blocking. As the TFTs performed programming and erasing operations, a large memory window observed from the V_G-I_D transfer curve was caused by electron and hole injection through a thin tunneling layer of oxynitride (Si O_x N_y). We also achieved a low driving voltage and short time duration for programming and erasing operations. Our results, based on retention evaluation, showed suitable operation performance after 10 ⁴s.