Schottky contact modulation at a-GeSe/TiN interface for ovonic switching selectors

• A high Schottky barrier height type contact is found for TiN/amorphous-GeSe. • The layer of amorphous-Carbon imparts a reduction of the Schottky barrier height with lower threshold voltage and higher leakage current. • The insertion of the a-C interlayer inhibits the diffusion of Ti into the chalcogenide layer. • The contact between a-C and TiN substrate is Ohmic like. This ensures an electrical current flow without any significant potential drops. The use of amorphous GeSe-based chalcogenides in ovonic threshold switching selectors for highly efficient phase-change memory devices involves the formation of contacts with metal electrodes, where the nature of interfacial contact plays a crucial role in controlling the power efficiency. Here, by using a joint experimental-theoretical approach we study the key contact properties between TiN-electrode and amorphous GeSe (a-GeSe) semiconductor. Two types of stackable devices with and without amorphous carbon (a-C) interlayer film were investigated; namely, TiN/a-GeSe and TiN/a-C/a-GeSe stacks. The interfacial contact between TiN electrode and a-GeSe is characterized by a high Schottky barrier height (SBH) type contact. The insertion of the Carbon buffer layer develops a lower SBH with a-GeSe, leading to a higher leakage current and a lower V TH , in line with the experimental observation.