Ultrathin-Body TiO2 Thin Film Transistors With Record On-Current Density, ON/OFF Current Ratio, and Subthreshold Swing via O2 Annealing

In this letter, we report ultrathin-body (~15 nm) TiO
₂
thin film transistors (TFTs) with unprecedented electrical performance: ON-current density (
$I_{\text{on}}$
) of 16.7 mA/mm, ON/OFF current ratio (
$I_{\text{ON}}/I_{\text{OFF}}$
) of
$1.2 \times 10^{9}$
and subthreshold swing (SS) of 101 mV/dec. The TiO
₂
channel layer was deposited by thermal atomic layer deposition (ALD) followed by post-annealing in O
₂
ambient. The material characterizations indicate the formation of anatase TiO
₂
polycrystalline films and a lack of detectable oxygen vacancies, which could have acted as charging traps in channel and channel/dielectric interface, benefiting the
$I_{\text{ON}}$
and the SS. These high-performance ultrathin-body TiO
₂
TFTs open a new venue in many applications such as high-resolution display and radiofrequency identification (RFID) tag, where high on currents and steep SS are required.