TCAD Design and Performance Simulation of FeFETs

• Orlando Hernandez, Electrical Engineering, University of Delaware

• Yuping Zeng, Electrical and Computer Engineering, University of Delaware
• Zijun Chen, , University of Delaware

Ferroelectric field-effect transistors (FeFETs) integrate a thin ferroelectric layer into a standard transistor to store data non volatilely. This means they remember a 1 or 0 even when powered off. We need FeFETs because they combine fast logic operations with built-in memory This enables electronics that come on instantly, remembers the state it was previously in, and allows for lower power consumption. Early FeFETs used materials like PZT, but hafnium-zirconium oxide (HZO) is preferred. It switches reliably at thicknesses below 10 nm, crystalizes at lower temperatures, and fits existing chip-making tools.

Gallium nitride (GaN) offers a wide bandgap, high breakdown voltage, and thermal stability. This has advantages for high voltage, high temperature, and high frequency operations. Combining GaN with a layer of HZO allows for the higher voltages and temperatures of GaN but with the ability to remember the previous state provided by HZO. You can also improve the frequency and performance of GaN by adding a thin layer of a wider gap material (e.g. AlGaN). This allows electrons to flow with very little scattering boosting the speed. Together, these materials allow GaN based devices to leverage the best of both worlds, power, speed, and instant memory.

In our Sentaurus TCAD workflow, we apply a DC gate-voltage sweep to obtain the ID – VG transfer curve and use that same DC-VG input to drive and capture the ferroelectric PX -|EX| hysteresis loop. This lets us directly correlate the transistor’s transfer behavior with the underlying polarization switching dynamics. These results guide further optimization of device performance and functionality.