Self-Aligned Indium–Gallium–Zinc Oxide Thin-Film Transistor With Phosphorus-Doped Source/Drain Regions

Self-aligned top-gate amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with phosphorusdoped source/drain regions are developed in this letter. The resulting a-IGZO TFT exhibits high thermal stability and good electrical performance, including field-effect mobility of 5 cm²/V · s, a threshold voltage of 5.6 V, a subthreshold swing of 0.5 V/dec, and an on/off current ratio of 6 × 10⁷. With scaling down of the channel length, good characteristics are also obtained with a small shift in the threshold voltage and no degradation in the subthreshold swing.