High-Performance Amorphous Indium Gallium Zinc Oxide Thin-Film Transistors Fabricated by Atomic Layer Deposition

This letter reports the fabrication of high-performance amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) via atomic layer deposition at a substrate temperature of 250 °C. The film thickness of In
₂
O
₃
, Ga
₂
O
₃
, and ZnO varied linearly with the number of deposition cycles. The cation composition of the IGZO film was controlled by an alternate stacking of In
₂
O
₃
, Ga
₂
O
₃
, and ZnO atomic layers. The fabricated a-IGZO TFTs exhibited a high electron mobility of 22.1 cm
²
/Vs, threshold voltage of 2.41 V, subthreshold gate swing of 0.30 V/decade, and an
${I}_{{ \mathrm{\scriptscriptstyle ON}}/{ \mathrm{\scriptscriptstyle OFF}}}$
ratio of
$> \textsf {1} \times \textsf {10}^{\textsf {8}}$
.