Ferroelectric field effect transistor with a double-gate structure on AlGaN/GaN heterostructures

The ferroelectric effect has been demonstrated on an AlGaN/GaN heterostructure field effect transistor using a Pb(Zr0.52Ti0.48)O3 layer deposited by radio-frequency magnetron sputtering. The device with a metal-ferroelectric-metal-semiconductor (MFMS) structure was fabricated with a Schottky contact placed between ferroelectric PZT and AlGaN/GaN 2-dimensional electron gas (2DEG) channel. The Schottky contact performs as a bottom electrode of the ferroelectric PZT and also as a barrier layer to prevent interaction at the interface between PZT and GaN. X-ray diffraction revealed the formation of (111)-oriented perovskite phase PZT on gate patterned AlGaN/GaN heterostructures. Transfer characteristics of the double-gate ferroelectric field effect transistor was determined by measuring its source-drain current as the gate bias applied on the top electrode was swept from -15 V to 15 V and then back to -15 V with a voltage step of 0.1 V. Ferroelectric behavior was observed in the plot of source-drain current versus gate voltage that showed a large counterclockwise hysteresis with a 50 % current modulation at zero gate bias.