Low operating voltage ambipolar graphene oxide-floating-gate memory devices based on quantum dots
Solution processed quantum dots (QDs) were employed as semiconductor layers in low operating voltage nonvolatile memory devices where graphene oxide (GO) was embedded as a charge storage element. Ambipolar PbSe QD layers have the ability to intrinsically transport holes and electrons, which provides an opportunity for the GO layers to trap both holes and electrons efficiently, resulting in bidirectional threshold voltage shifts after the program/erase operations are applied. The memory exhibited a large memory window (ΔVon ∼ 6 V) and a long retention time (>104 s) under low program/erase operating voltages of ±25 V. The magnitude of ΔVon is controlled not only by programming/erasing voltages (VP/E) but also by the bias voltage (VDS), where ΔVon shows a quadratic function to VP/E and linearly depends on VDS. The QD based GO-floating-gate memory devices supply a facile route for fabricating flexible devices with low-cost large-scale integration.