Long-retention ferroelectric-gate FET with a (HfO/sub 2/)/sub x/(Al/sub 2/O/sub 3/)/sub 1-x/ buffer-insulating layer for 1T FeRAM

A ferroelectric-gate FET (FeFET) is significant for 1T FeRAM. Among fabricated Pt/SrBi/sub 2/Ta/sub 2/O/sub 9//(HfO/sub 2/)/sub x/(Al/sub 2/O/sub 3/)/sub 1-x//Si FeFETs, we find that the optimum buffer-layer composition ratio, x, of HfO/sub 2/ and Al/sub 2/O/sub 3/ exists around 0.75. A FeFET of x = 0.75 with high k buffer layer and low leakage current shows long data retention.