BEOL Compatible Indium-Tin-Oxide Transistors: Switching of Ultra-High-Density 2D Electron Gas over 0.8×10 14 /cm 2 by Ferroelectric Polarization

In this work, we report back-end-of-line (BEOL) compatible indium-tin- oxide (ITO) transistors with ferroelectric Hf0.5Zr0.5O2 (HZO) as gate insulator. A tunable high-density two-dimensional (2D) electron gas over 0.8×1014 /cm2 is achieved at the HZO/ITO oxide/oxide interface because of the ferroelectric polarization, which is confirmed by I-V, positive up and negative down (PUND) and Hall measurements. Such high carrier density can be completely modulated and switched on and off by ferroelectric polarization switching, enabling high mobility ITO transistor with high on- current and high on/off ratio.