Nonvolatile Charge-Trap Memory Transistors With Top-Gate Structure Using In–Ga–Zn-O Active Channel and ZnO Charge-Trap Layer

We proposed a charge-trap-type memory transistor with a top-gate structure composed of Al₂O₃ blocking/ZnO charge-trap/IGZO active/ Al₂O₃ tunneling layer. The memory ON/OFF ratio higher than six-orders-of magnitude was obtained after the programming when the width and amplitude of program pulses were 100 ms and ±20 V, respectively. Excellent endurance was successfully confirmed under the repetitive programming with 10⁴ cycles. The memory ON/OFF ratio higher than 10³ was guaranteed even after the lapse of 10⁴ s. Interestingly, the retention properties were affected by the bias conditions for read-out operations.