Low-frequency noise in gate overlapped lightly doped drain polycrystalline silicon thin-film transistors

Low-frequency noise has been investigated in gate overlapped lightly doped drain (GOLDD) polysilicon thin-film transistors (TFTs). We found that as in self-aligned polycrystalline silicon (polysilicon) TFTs, the low-frequency noise GOLDD polysilicon TFTs originates from carrier number fluctuations. In addition, no excess noise was observed when measuring GOLDD TFTs in the kink regime, in contrast to what was observed in self-aligned polysilicon TFTs. This has been explained by attributing the excess noise to supplemental oxide charge fluctuations induced by hot-carrier injection into the gate oxide and showing, by using two-dimensional numerical simulations, that the hot-electron emission current in GOLDD polysilicon TFTs can be much lower than in conventional drain contact configurations. (C) 2000 American Institute of Physics. [S0003-6951(00)02720-0].