Surface-controlled ultrathin (2 nm) Poly-Si channel junctionless FET towards 3D NAND flash memory applications

An ultrathin junctionless (JL) charge trap flash (CTF) thin-film transistor (TFT) with a sub-2 nm thick poly-Si channel is demonstrated for 3D stacked flash memory. It provides the excellent memory performance of faster program/erase (P/E) speed, larger memory window (>12 V), and better endurance (>10⁴ cycles) than inversion-mode (IM) devices; this device also has excellent 10-year data retention at 150 °C, as well as improved on/off current ratio (>10⁸) and subthreshold swing (SS). The transfer characteristics and the memory performance as a function of the poly-Si channel thickness (T_Ch) are also systematically investigated.