Anomalous Phase Change in SbSe_x Memristors for Ultrafast Image Encryption

Complex electrical nonlinearity process in neurons is believed to be the origin of high-level cognition, highly desired for an electronic device with rich dynamics. Here, an anomalous phase transition in the semiconducting SbSe_x thin film is observed in situ, which includes not only the conventional phase transition process (amorphous to crystalline) but also involves the Sb metallic nucleus growth that has never been observed before. Theoretical simulation results show that when Sb or Se vacancies are introduced into the SbSe_x, Joule heat will accumulate near the vacancy centers, causing an anomalous phase transition in a localized region, thereby giving the defective memristor a unique N-shape negative differential resistance (NDR) effect. These rich nonlinear electric switching dynamics provide a chaotic system for ultra-fast image encryption that is at least two orders of magnitude faster than current techniques. This work builds a novel theory horizon as well as extends brand-new application area of phase change electronics.