ZnO nanowire-based nonvolatile memory devices with Al ₂0 ₃ layers as storage nodes

Top-gate ZnO nanowire field-effect transistors (FETs) with Al ₂0 ₃ gate dielectric layers as storage nodes were fabricated and their memory effects were characterized in this work. The Al ₂0 ₃ layers deposited on the ZnO nanowire channels were utilized not only as gate dielectric ones but also as charge trapping ones. For a representative top-gate ZnO nanowire FET, its l _DS-V _GS characteristics for the double sweep of the gate voltages exhibit the counterclockwise hysteresis and the threshold voltage shift. The gate voltage in the pulse form was applied for 1 s, and the threshold voltage shift of l _ds-V _GS characteristics was extended from 0.3 to 0.8 V compared with that for the double sweep. In this ZnO nanowire FET, negative charge carriers originated from the gate electrode are stored in the Al ₂0 ₃ layer for applied negative gate voltages, and they are extracted for applied positive gate voltages.