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Title Impacts of Bottom-gate Bias Control for Low-voltage Memory Operations of Charge-trap Memory Thin Film Transistors using Oxide Semiconductors
Authors Min-Tae Son(Min-Tae Son) ; So-Jung Kim(So-Jung Kim) ; Sung-Min Yoon(Sung-Min Yoon)
Page pp.69-78
ISSN 1598-1657
Keywords Oxide thin film transistors ; double gate ; charge trap memory ; memory retention
Abstract We fabricated and characterized the double-gate (DG) charge-trap memory thin film transistors (CTM-TFTs) using In-Ga-Zn-O active and ZnO charge-trap layers. The fabricated device exhibited a charge-trap-assisted memory window as wide as 13.8 V using a DG mode operation and a program/erase (P/E) speed faster than 10 μs. These memory device characteristics were examined by controlling the fixed bias voltage applied at the bottom gate (VBG) and the capacitance coupling ratio between top and bottom gate insulators, which could be strategically designed with the DG configuration. The capacitance coupling ratio was varied by changing the bottom gate insulator (BGI) thickness between 50 and 100 nm. For the CTM-TFT with a BGI thickness of 100 nm, 3.1×106 was obtained for the memory on/off ratio with P/E voltages of ± 15 V and a fixed VBG of -3 V. Overall, our results suggest that the DG configuration can remarkably enhance the P/E speed and memory on/off ratio by suitably controlling the fixed VBG conditions and the capacitance coupling ratio in CTM-TFTs.