Ultra-Low Current 10 nm Spin Hall Nano-Oscillators

Area of Science:

• Spintronics
• Nanotechnology
• Materials Science

Background:

• Spin Hall nano-oscillators (SHNOs) are key for neuromorphic computing.
• Miniaturization of SHNOs below 50 nm faces challenges with threshold current scaling.
• Current shunting through Si substrates limits SHNO performance.

Purpose of the Study:

• Investigate the origin of poor threshold current scaling in nano-constricted SHNOs.
• Explore the use of seed layers to mitigate current shunting.
• Enable miniaturization of SHNOs to truly nanoscopic dimensions.

Main Methods:

• Fabrication of nano-constricted SHNOs with varying seed layers on p-Si substrates.
• Characterization of SHNO performance, focusing on threshold current.
• Analysis of current shunting effects through the Si substrate.

Main Results:

• Identified current shunting through the Si substrate as the primary cause of poor scaling.
• Demonstrated that an ultra-thin Al2O3 seed layer significantly improves SHNO performance.
• Achieved 10 nm width SHNOs operating at threshold currents below 30 µA.
• Showcased Al2O3's dual benefit of electrical insulation and thermal conductivity for large arrays.

Conclusions:

• Ultra-thin Al2O3 seed layers effectively mitigate current shunting in nano-constricted SHNOs.
• This enables unprecedented miniaturization of SHNOs to 10 nm with ultra-low operating currents.
• The developed SHNOs offer an energy-efficient pathway for scaling oscillator-based computing, including large dynamical neural networks and 2D arrays.