Extended endurance performance and reduced threshold voltage by doping Si in GeSe-based ovonic threshold switching selectors

Abstract

Selectors are essential part of the high-density storage architectures to operate the storage device in the crossbar arrays by providing a desired net voltage drop and suppressing undesired current flow. Germanium selenide -based Ovonic Threshold Switching (OTS) selector shows a promising candidate for simple binary composition and high selectivity, however, the high threshold voltage and thermal budget lower than required for Complementary Metal Oxide Semiconductor process are needed to overcome. In this paper, we demonstrate the effect of silicon doping Ge42Se58 thin films on their electrical characteristics of OTS devices and the electronic structure of materials. Si doping allows low threshold voltages ranging from 1.5 to 3 V and improved thermal stability, Si-Ge-Se with Si 13% can cycle steadily more than 5 × 106 cycles. In addition, the optical energy gap of films decreases with increasing Si content. These results, being interpreted as Si atoms modify the bonding type of Ge42Se58 thin film as well as electronic structure includes the energy gap and trap states, suggest an effective method to modulate threshold voltage of the GeSe-based selector by using Si as dopant for various OTS device applications. According to the unified analytical model (Poole-Poole-Frenkel) based on trap-limited conduction, the trap density of Si-Ge-Se thin films in the switching process decreases from 1.29×1017cm−3 to 2.88×1016cm−3with increasing Si content.