Numerical Investigation of Short-Channel Effects and RF Performance in Top-Gate In₂O₃ Thin-Film Transistors.

Area of Science:

• Materials Science and Engineering
• Semiconductor Device Physics
• Nanotechnology

Background:

• Indium oxide (In2O3) is a promising semiconductor with high electron mobility and a wide bandgap, suitable for advanced electronics.
• Understanding the lateral scaling behavior of In2O3 thin-film transistors (TFTs) is crucial for optimizing their performance in scaled devices.

Purpose of the Study:

• To investigate the lateral scaling characteristics of top-gate In2O3 TFTs with ultrathin channels and HfO2 gate dielectrics.
• To analyze short-channel effects, DC characteristics, transconductance, and radio frequency (RF) performance as a function of gate length (LG).

Main Methods:

• Two-dimensional device simulations were employed to study In2O3 TFTs with gate lengths ranging from 20 nm to 700 nm.
• Analysis included short-channel effects (VTH shift, DIBL), DC and transconductance behavior, and RF metrics (fT, fmax).

Main Results:

• A critical gate length near 100 nm was identified, marking the transition to pronounced short-channel effects, including significant negative VTH shift and high DIBL (>130 mV/V).
• Observed non-classical gm scaling behavior, attributed to the interplay of field-assisted transport and gate-controlled modulation.
• Achieved high RF performance with fT and fmax reaching 124.32 GHz and 157.64 GHz at LG = 20 nm, respectively.

Conclusions:

• Ultrathin In2O3 TFTs exhibit complex scaling behavior due to short-channel effects and unique transport mechanisms.
• The devices demonstrate significant potential for high-frequency and power-dense applications, driven by the high-mobility In2O3 channel.
• This study provides critical physical insights into the lateral scaling limits and RF capabilities of In2O3 TFTs for future electronic designs.