Threshold switching in chalcogenide GeTe and GeTeS thin films prepared via plasma enhanced atomic layer deposition

In this study, atomic layer deposition processes were developed for application of chalcogenide GeTe_x and GeTe_xS_1−x thin films in threshold switching devices. Owing to the low controllability of chemical compositions of thin films with a given precursor, and to achieve an optimal chemical composition for favorable electrical performance of threshold switching devices, the super-cyclic atomic layer deposition process was adopted using a combination of Ge-Te, Te-Te, and Ge-S sub-cycles. In the electrical test, the S-doped GeTe_x thin film-based threshold switching device showed an enhanced electrical performance than that without S. By analyzing the temperature dependent current-voltage characteristics and X-ray photoelectron spectroscopy, it was discovered that the improved electrical characteristics in the S-doped GeTe_x thin film are caused by the narrow energy distribution and increased energy depth of electron traps. The results of this study can guide the fabrication of 3D structured electronic devices with high integration densities in the fields of next-generation memory and brain-inspired neuromorphic applications.