Multilevel characteristics and memory mechanisms for nonvolatile memory devices based on CuInS2 quantum dot-polymethylmethacrylate nanocomposites

Abstract

Nonvolatile memory devices based on CuInS2 (CIS) quantum dots (QDs) embedded in a polymethylmethacrylate (PMMA) layer were fabricated using spin-coating method. The memory window widths of the capacitance-voltage (C-V) curves for the Al/CIS QDs embedded in PMMA layer/p-Si devices were 0.3, 0.6, and 1.0V for sweep voltages of +/- 3, +/- 5, and +/- 7V, respectively. Capacitance-cycle data demonstrated that the charge-trapping capability of the devices with an ON/OFF ratio value of 2.81 x 10(-10) was maintained for 8 x 10(3) cycles without significant degradation and that the extrapolation of the ON/OFF ratio value to 1 x 10(6) cycles converged to 2.40 x 10(-10), indicative of the good stability of the devices. The memory mechanisms for the devices are described on the basis of the C-V curves and the energy-band diagrams.