Switching Mechanisms of Nonvolatile Memory Devices Fabricated with a Polydopamine Layer

Nonvolatile memory devices based on a polydopamine (PDA) layer were fabricated by using a dip-coating process. Atomic force microscopy images revealed that the PDA layer had a conformal surface. The energy dispersive X-ray data showed the atomic stoichiometry of nitrogen and carbon in the PDA layer. The capacitance-voltage (C-V) curves of the Al/PDA/n-Si memory devices at 300 K showed a hysteresis with a large flat band shift, indicating that the incomplete PDA layer acted as a charge storage in the memory device. The switching mechanisms for the writing and erasing processes for the Al/PDA/n-Si devices are described on the basis of the C-V results and the energy band diagrams.