Vertically Stackable Ovonic Threshold Switch Oscillator Using Atomic Layer Deposited Ge_0.6Se_0.4 Film for High-Density...

Area of Science:

• Materials Science
• Computer Engineering
• Neuroscience

Background:

• Nanodevice oscillators (nano-oscillators) are crucial for neuromorphic computing, offering higher integration density and energy efficiency than traditional circuits.
• Ovonic threshold switch (OTS) devices show promise for implementing nano-oscillators in advanced hardware.
• Current fabrication methods face limitations in achieving high-density vertical integration.

Purpose of the Study:

• To demonstrate vertically stackable nano-oscillators using an ovonic threshold switch (OTS) for high-density neuromorphic hardware.
• To develop a fabrication process for integrating these nano-oscillators into vertical crossbar arrays.
• To evaluate the potential of these devices for implementing spiking neural networks (SNNs) and oscillatory neural networks (ONNs).

Main Methods:

• Fabrication of a vertically stackable Ge_0.6Se_0.4 OTS-oscillator (VOTS-OSC) using atomic layer deposition in a vertical crossbar array structure.
• Conformal growth of Ge_0.6Se_0.4 film on a contact hole structure.
• Characterization of oscillation characteristics and thermal stability (<400 °C fabrication temperature).

Main Results:

• Successful fabrication of VOTS-OSC devices exhibiting oscillation characteristics.
• Demonstration of VOTS-OSC suitability as leaky integrate-and-fire neurons for SNNs and coupled oscillators for ONNs.
• Semiempirical simulations showing successful pattern recognition (SNNs) and vertex coloring (ONNs) using the fabricated devices.

Conclusions:

• The VOTS-OSC structure significantly increases oscillator integration density, enabling complex neuromorphic tasks.
• Vertical integration is achieved without thermal damage to peripheral circuits due to low fabrication temperatures.
• The rapid switching speed of these nano-oscillators enhances the computational speed of neural networks.