Low-Frequency Noise Properties in Double-Gate Amorphous InGaZnO Thin-Film Transistors Fabricated by Back-Channel-Etch Method

We investigated the low-frequency noise (LFN) properties of double-gate (DG) amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). The LFN from all of the DG, top-gate (TG), and bottom-gate (BG) operation modes was well explained in the framework of the correlated carrier number-mobility fluctuation. However, the extracted noise parameters of the border trap density (N
_T
), Coulomb scattering coefficient (α
_S
), and apparent noise parameter (α
_app
) exhibited the highest values during the TG operation mode and the lowest values during the DG operation mode. The higher noise parameters (N
_T
, α
_S
, and α
_app
) from the TG operation mode compared with those from the BG operation mode were attributed to the poorer quality of the TG interface than the BG interface in the fabricated back-channel-etch-type DG a-IGZO TFTs. During the DG sweeping operation, the formation of the bulk accumulation channel was observed. The lowest noise parameters (N
_T
, α
_S
, and α
_app
) from the DG operation mode were considered to be a result of the current conduction through the bulk accumulation channel with a relatively low oxygen vacancy-related trap concentration.