Low Operating Voltage InGaZnO Thin-Film Transistors Based on Al_2O_3 High-k Dielectrics Fabricated Using Pulsed Laser Deposition

摘要

Low-voltage-driven amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) with an Al_2O_3 dielectric were fabricated on a Si substrate by using pulsed laser deposition. Both Al_2O_3 and IGZO thin films are amorphous, and the thin films have very smooth surfaces. The Al_2O_3 gate dielectric exhibits a very low leakage current density of 1.3 × 10~(?8) A/cm~2 at 5 V and ahigh capacitance density of 60.9 nF/cm~2. The IGZO TFT with a structure of Ni/IGZO/Al_2O_3/Si exhibits high performance with a low threshold voltage of 1.18 V, a high field effect mobility of 20.25 cm~(2V?)1s~(?1), an ultra small subthreshold swing of 87 mV/decade, and a high on/off current ratio of 3 × 10~7.