A tellurium-free GeSbSe thin film for reliable selector-only memory operation

Abstract

Selector-only memory (SOM) devices are promising candidates for non-volatile memory units with high-density crossbar array architectures due to their simple two-terminal configuration, compatibility with two-terminal architectures, and the elimination of the need for separate selector-storage layers. These advantages reduce fabrication complexity, minimize cell footprint, and enable low-power operation. To date, most SOM devices have been based on tellurium (Te)-containing chalcogenide materials, in which Te atoms act as essential trigger elements, enabling field-driven switching due to their highly polarizable p-orbitals. However, the intrinsic properties of Te also introduce critical limitations, including poor thermal stability, high leakage current, and a narrow read window margin (RWM), which constrain device reliability and scalability. To overcome these challenges, a Te-free amorphous material, GeSbSe (GSS), has been developed to preserve desirable threshold switching behavior. The GSS-based SOM device exhibits a wide RWM (2 V), reliable operation at fast operation speeds (50 ns), and ultra-low write-pulse current (10 µA), indicating its potential for high-speed and low-power operation. Furthermore, a Te-containing counterpart, GeSbSeTe (GSST), was fabricated and systematically characterized to investigate the detrimental impact of Te incorporation on the electrical characteristics. By evaluating various electrical performance metrics, the electrical degradation of SOM devices induced by Te incorporation was systematically evaluated. A comparative analysis with the Te-free GSS counterpart highlights the adverse effects of Te on device stability and switching uniformity, offering insights into the design of more reliable SOM devices.