An Amorphous Native Oxide Shell for High Bias-Stress Stability Nanowire Synaptic Transistor

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Inhomogeneous native oxide shells on III-V semiconductors degrade electrical properties, impeding advanced integrated circuits.
• Gallium antimonide (GaSb) nanowires (NWs) are promising for next-generation electronics but suffer from surface instability.

Purpose of the Study:

• To utilize native gallium oxide (GaOx) shells via in-situ thermal annealing to enhance GaSb nanowire field-effect transistors (FETs).
• To investigate the resulting bias-stress stability and synaptic behaviors for neuromorphic computing applications.

Main Methods:

• A simple in-situ thermal annealing process was applied to GaSb NWs with native GaOx shells.
• Optimized annealing time (5 min) was determined to achieve superior device performance.
• Bias-stress stability was evaluated under prolonged gate bias stress.
• The annealed NW FETs were tested for synaptic behaviors, including plasticity and learning stability.

Main Results:

• Optimal annealing significantly improved bias-stress stability, reducing the threshold voltage shift (ΔVth) from 8.2 V to 0.54 V after 60 min of gate bias.
• The annealed GaSb NW FETs exhibited robust synaptic functionalities, including short-term and long-term plasticity, and spike-time-dependent plasticity.
• Mobile oxygen ions in the GaOx shell were identified as key to offsetting trapping states, enhancing stability and charge retention.

Conclusions:

• In-situ thermal annealing of native GaOx shells is an effective strategy for fabricating high-performance and stable GaSb NW FETs.
• These stable FETs demonstrate potential as chargeable-dielectric-free synaptic devices for neuromorphic computing.
• This approach offers a novel method for leveraging native oxide shells to overcome stability challenges in semiconductor devices.