Scaling of coplanar homojunction amorphous In-Ga-Zn-O thin-film transistors

Channel length (L) and width (W) scaling of amorphous In–Ga–Zn–O (a-IGZO) thin-film transistors (TFTs) have been investigated by coplanar homojunction a-IGZO TFTs. The fabricated TFTs have a mobility around 12 cm2 V-1 s-1, sub-threshold slope (S) of ~110 mV/decade, threshold voltage around 0.3 V and off-current below 10-13 A. The TFTs with L > 5 µm have the reduced transconducance (gm) at lower VGS, however, the short L < 5 µm TFTs have the gm reduction at higher VGS. Even though the TFTs with smaller channel length (L ≤5 µm) show proper switching characteristics, threshold voltage lowering and sub-threshold slope degradation are clearly observed.