Screening Switching Materials with Low Leakage Current and High Thermal Stability for Neuromorphic Computing

Abstract

Neuromorphic computing implemented with spiking neural networks is an energy efficient computing paradigm to break through the Von Neumann bottleneck in the future. Ovonic threshold switching (OTS) selector is considered to be a promising spiking neuron candidate. As ≈1011 artificial neurons are needed for brain‐inspired computing, leakage current of OTS devices would waste enormous power. OTS devices with ultralow leakage current are deeply desired. Since the leakage current is closely related to the bandgap of OTS materials and only the amorphous one shows the volatile switching property, here binary gallium sulfide (GaS), characterized by 2.53 eV large band‐gap and ≈550 °C high crystallization temperature is singled out, as the most appealing OTS material. High‐density trap states, an essential prerequisite of the OTS material, are detected in the amorphous GaS. Indeed, the OTS behaviors of the GaS‐based device are directly observed. The simple OTS device could provide 21.23 MA cm−2 large ON current density, and ≈10−8 A low OFF current and ≤10 ns switching speed. Furthermore, it is also used to build GaS‐based leakage integrate and fire neurons for future neuromorphic computing. This study provides a new idea for material design before device preparation and takes a neuron as an example.

Great Potential of Si-Te Ovonic Threshold Selector in Electrical Performance and Scalability

“…However, loads of materials with superior performance emerging from the OTS research in full swing contain eco-unfriendly elements such as sulfur [ 8 , 9 , 10 ], arsenic [ 11 , 12 ] etc. ; additionally, most OTS materials are ternary, quaternary or even more [ 13 , 14 ], which means they inevitably suffer from element segregation and inhomogeneous composition.…”

A refresh operation method for solving thermal stability issues and improving endurance of ovonic threshold switching selectors

“…Up to now, there have been many studies on OTS materials, which are recognized to be based on chalcogenide compounds (S, Se, and Te-based alloy). 6,[23][24][25][26][27][28] However, undoped binary systems usually have low thermal stability and cannot meet the requirement for the BEOL process. Methods to improve OTS thermal stability include element doping 29 and introducing a multilayered structure.…”

Improving the GeAsSe Ovonic Threshold Switching Characteristics by Carbon Buffer Layers for Ultralow Leakage Current (∼0.4 nA) and Low Drift Characteristics

“…An access device has proved pivotal in solving the data disturbance issue, such as a selector . For certain amorphous chalcogenide alloys containing S, Se, − and Te , elements, also known as Ovonic threshold switching (OTS), once the applied voltage exceeds the critical value (threshold voltage, V th ), the high-resistance state (OFF-state) fast switches to the conductive state (ON-state) without changing the phase. The OTS material recovery after its OFF-state removes the voltage.…”