Temperature-stable nonvolatile memory operation in silicon carbide field-effect transistors: simulation and experiment

Jo, Yeong-Deuk1; Choi, Chang-Yong1; Lee, Jae-Sang1; Park, Joon-Sung1; Koh, Jung-Hyuk1; Ha, Jae-Geun1; Koo, Sang-Mo1; Khartsev, Sergey2; Zetterling, Carl-Mikael2; Lee, Hyung-Seok2; Domeij, Martin2; Grishin, Alex2; Östling, Mikael2 1Republic of Korea; 2Sweden

In this work, we show that a silicon carbide (SiC) dual-gated field effect transistor (FET) enables non-volatile memory operation for both data storage and data processing at elevated temperatures.
Because of its large band gap and inherent materials properties, SiC shows high values for breakdown field and saturation drift velocity as well as low values for intrinsic carrier concentration and permittivity. Thus SiC semiconductor devices have been established as very useful high power, high speed and high temperature devices.
We have fabricated dual-gated nonvolatile FETs with a backside pn junction-gate (G1) and a top ferroelectric PZT gate (G2). In this device G1 controls the drain current effectively from the buried junction gate thereby allowing for a constant current level at different temperatures depending on the off-set bias applied, whereas G2 enables a nonvolatile memory operation induced by the polarization of ferroelectric PZT gate stack. It has been tested at both room temperature and elevated temperatures (up to 300oC), to demonstrate full nonvolatile programmability. The room temperature memory window as large as 7 V has been demonstrated and the constant on/off current level operation has been maintained at all tested temperatures. The ferroelectric hysteresis induced charging/discharging effect has also been studied by using 2-dimensional numerical device simulation and the advantages of the proposed device structures are discussed to highlight the need for development of memory cells and sensors for operation in harsh environments.

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