Improvement in Short-Channel Effects of the Thin-Film Transistors Using Atomic-Layer Deposited In–Ga–Sn–O Channels With Various Channel Compositions

In–Ga–Sn–O (IGTO) thin-film transistors (TFTs) were fabricated with channel lengths from
$3 \mu \text{m}$
to 500 nm to investigate the short-channel effects (SCEs), in which IGTO channel compositions were modulated during the atomic-layer deposition. The SCEs appearing in the IGTO TFTs were found to be manifested by increasing the In/Ga ratio of IGTO channel, showing typical channel composition dependence. Alternatively, small values of the channel-length reduction and contact resistance could be obtained to be 50 nm and 0.52
$\text{k}\Omega $
, respectively, for the device using the IGTO channel with an In/Ga ratio of 1.7. Threshold voltage shifts of the IGTO TFT were estimated to be only +0.03 and +1.22 V under negative and positive gate-bias stress for 104 s, respectively, even with a channel length as short as
$1 \mu \text{m}$
.