High-Performance Amorphous InGaZnO Thin-Film Transistors With HfO2/Lu2O3/HfO2 Sandwich Gate Dielectrics

In this brief, a high-performance amorphous InGaZnO (α-IGZO) thin-film transistor (TFT) with a HfO
₂
/Lu
₂
O
₃
/HfO
₂
(HLH) sandwich gate dielectric is demonstrated for the first time. Compared with the Lu
₂
O
₃
dielectric, the α-IGZO TFT device using an HLH sandwich gate dielectric exhibited a low threshold voltage of 0.43 V, a high field-effect mobility of 17.2 cm
²
/Vs, a small subthreshold swing of 104 mV/decade, and a high I
_ON
/I
_OFF
current ratio of 3.08 × 10
^-7
, presumably because of the reduction of surface roughness at the dielectric-channel interface. Furthermore, the reliability of voltage stress can be improved using an HLH sandwich dielectric structure.