Nonvolatile low-voltage memory transistor based on SiO₂ tunneling and HfO₂ blocking layers with charge storage in Au nanocrystals

We demonstrate a low voltage nonvolatile memory field effect transistor comprising thermal SiO₂ tunneling and HfO₂ blocking layers as the gate dielectric stack and Au nanocrystals as charge storage nodes. The structure exhibits a memory window of ∼2 V at an applied sweeping voltage of ±3 V which increases to 12.6 at ±12 V. Retention tests show an extrapolated loss of 16% after ten years in the hysteresis width of the threshold voltage. Dynamic program/erase operation reveal an approximately pulse width independent memory for pulse durations of 1 μs to 10 ms; longer pulses increase the memory window while for pulses shorter than 1 μs, the memory windows vanishes. The effective oxide thickness is below 10 nm with very low gate and drain leakage currents.