Forming-Free Selectors Based on Te in an Insulating SiO_x Matrix

Low voltage and low off-current selectors are needed to meet the requirements for cross-point array architectures in embedded memories. Chalcogenide-based selectors have been widely studied for such applications, but no single material system has yet demonstrated all the specifications required for integration with nonvolatile memory. This article presents arsenic-free selectors based on a simple and stable material system consisting of Te in an insulating SiOx matrix. By modifying the thickness and atomic composition of films, tunable switching voltage and off-current are achieved. Optimized forming-free SiOx Te y selectors are demonstrated with a threshold voltage of similar to 1.2 V and an off-current of similar to 3 nA at 0.5 V. Size-and temperature-dependent measurements provide insight into the different conduction mechanisms of devices with different forming behaviors. Threshold voltage drift of similar to 30 mV/decade is measured for both forming-required and forming-free devices. These selectors maintain their functionality after a 300 C-degrees anneal and a recovery pulse, and they are stable after one year stored in air. Excellent endurance of > 10(11 )cycles is reported, making these devices promising for integration with nonvolatile memory.