A vertically integrated bipolar storage cell in 6H silicon carbide for nonvolatile memory applications

MOS capacitor on 4H-SiC as a nonvolatile memory element

“…Given that the intrinsic-carrier concentration of 4H-SiC is about 17 orders of magnitude lower compared to silicon, this retention time corresponds to 1.5 s in silicon, clearly indicating that the quality of the nitrided SiO -SiC interface (in terms of carrier-generation rate) is comparable to the SiO -Si interface. Comparing with the retention time (10 s or 3 10 years) obtained by Xie et al [7], it is also obvious that dramatic improvement in the quality of SiC-oxide interface is achieved. Consequently, the minority carrier generation through the SiO -SiC interface is reduced so much that the retention time of the MOS capacitor itself is three orders of magnitude longer.…”

“…Therefore, the time needed to generate minority carriers in 4H SiC should be 17 orders of magnitude longer than in Si [5] meaning that a MOS capacitor could operate as a nonvolatile RAM element with access characteristics of silicon dynamic RAM and retention characteristics of ROM. Gardner et al [6] and Xie et al [7] proposed a 6H-SiC memory element, where the potential well was created by n-p-n structure. They reported retention time of 10 s (3 10 years) at room temperature, as extrapolated from high-temperature measurements.…”

Comparison of charge–retention times in n- and p-type 4H–SiC MOS capacitors as non-volatile memory elements

“…According to the first-order Shockley-Read-Hall theory [12,13], the generation rate is proportional to n i . Thus, the generation rate in SiC is many orders of magnitude lower than in Si [8][9][10][11].…”

“…Silicon carbide has excellent physical and electrical properties [1,2] that enable it to be used as electronic material [3][4][5][6][7][8][9][10][11]. One of the interesting properties in this wide bandgap material (E g ¼ 3:26 eV in 4H SiC [2]) is the low concentration of intrinsic carrier (n i ) at room temperature (n i B10 À7 cm À3 in 4H SiC [2]) that contributes to the extremely low carrier-generation rate.…”