Chip-Scale Graphene/IGZO Cold Source FET Array Enabling Sub-60 mV dec^-1 Super-Steep Subthreshold Swing

Area of Science:

• Materials Science
• Semiconductor Physics
• Electronics Engineering

Background:

• Achieving steep subthreshold swing (SS) is crucial for low-power electronics.
• Traditional transistors face limitations in reducing SS due to thermal effects.

Purpose of the Study:

• To demonstrate a super-steep subthreshold swing (SS) below 60 mV/decade in graphene/InGaZnO (IGZO) cold-source field-effect transistor (CSFET) arrays.
• To investigate the impact of graphene's electronic properties and high-k dielectrics on SS performance.

Main Methods:

• Fabrication of graphene/IGZO CSFET arrays.
• Utilizing the linear density of states of Dirac-cone graphene to suppress thermal effects.
• Incorporation of HfO2 high-k dielectric with a low body factor for surface potential modulation.

Main Results:

• Demonstrated the first sub-60 mV/decade SS in graphene/IGZO CSFET arrays.
• Achieved a record SS value of 23.66 mV/decade.
• Obtained high uniformity with ≈89.1% yield for sub-60 mV/decade SS in 8x8 arrays.
• Observed super-exponential decay of electron density due to suppressed Boltzmann tail.

Conclusions:

• Graphene's unique electronic properties are effective in achieving ultra-low SS and off-current.
• HfO2 high-k dielectric further enhances SS performance.
• The developed IGZO CSFET technology promises advancements in high-speed and ultralow-power electronic circuits.