Characterization and Modeling of Co/BaTiO3/SrRuO3 Ferroelectric Tunnel Junction Memory by Capacitance–Voltage ( ${C}$ – ${V}$ ), Current–Voltage ( ${I}$ – ${V}$ ), and High- Frequency Measurements

Ferroelectric tunnel junction (FTJ) is a promising low power nonvolatile memory for beyond-CMOS applications. In this paper, Co/BaTiO
₃
/SrRuO
₃
FTJs are fabricated, simulated, and their electrical characteristics are measured by capacitance-voltage (C-V), current-voltage (I-V), and high-frequency S-parameter measurements. Ferroelectricity of the ultrathin BaTiO
₃
(~3.2 nm) film is first verified by a butterfly shaped hysteresis C-V profile, from which saturation polarizations are calculated in the ON state and OFF state as PON = +20 μC/cm
²
and POFF = -25 μC/cm
²
, respectively. The numerical simulation of the FTJ device is performed using experimental electronic band parameters of the heterostructure. The device structure was optimized for ON/OFF ratio, ION/IOFF = 75 for a depolarization field, Edpol <; 106 V/cm. The calculated tunnel currents of 250 nm×250 nm FTJ in ON state(ION = 130×10
^-9
A) and OFF state (IOFF = 1.75 × 10
^-9
A) match with experimental values. From the S-parameters of RF measurements, the high-frequency small-signal device model of the FTJ in ON state (CON = 5 fF, RON = 0.8 MΩ) and OFF state (COFF = 10 fF, ROFF = 70 MΩ) is developed for a frequency range from 50 MHz to 5 GHz. The extracted capacitor model of Co/BaTiO
₃
/SrRuO
₃
FTJ is useful for high-frequency simulation of benchmark FTJ circuits.