Negative Capacitance Oxide Thin-Film Transistor With Sub-60 mV/Decade Subthreshold Swing

In this letter, we demonstrate an integrated negative capacitance oxide thin-film transistor (NC-OTFT) based on ferroelectric Hf0.5Zr0.5O2 (HfZrO) film. The buried-gated TiN/HfZrO/Al2O3 structure is developed with indium zinc oxide as its channel. The transfer characteristics are measured with 1.2-V supply voltage. The NC-OTFT 15-nm HfZrO/6-nm Al2O3 shows 2.5 x 10(7) ON/OFF current ratio and 120-mV anticlockwise hysteresis. The subthreshold swing (SS) values of this NC-OTFT are lower than those of the control devices without HfZrO. The reverse SS shows sub-60 mV/decade about 2 orders of drain current. The minimal reverse and forward SS values are 52.8 and 74.1 mV/decade, respectively. The NC-OTFT with 8-nm HfZrO/6-nm Al2O3 is inspected with considerably narrower hysteresis of 50 mV. Its reverse and forward SS values reach as low as 63.6 and 69.8 mV/decade, respectively. The NC effect is observed in the gate-stack capacitance of the NC-OTFTs. This NC-OTFT is promising for low operating voltage and low power consumption applications.