Quasi-superlattice storage: A concept of multilevel charge storage

In this work, a novel concept of quasi-superlattice storage (QS ²) is demonstrated. Under a suitable operating voltage, two apparent states of charge storage can be distinguished. The memory effects are due to the multilevel charge storage within the quasi-superlattice. The multilevel charge storage provides a feasible design for the 2-bit-per-cell nonvolatile memory devices. Also, the leakage behavior of the quasi-superlattice structure has also been characterized by current-voltage measurements at room temperature and low temperatures. The resonant tunneling-like leakage characteristic is observed at low temperatures. A concise physical model is proposed to characterize the leakage mechanism of tunneling for the quasi-superlattice structure, and this suggests that consideration of the operating voltage for the 2-bit-per-cell nonvolatile memory device needs to be taken into account.