Flexible Gallium Nitride for High-Performance, Strainable Radio-Frequency Devices

Area of Science:

• Materials Science
• Electrical Engineering
• Solid State Physics

Background:

• Flexible electronics are crucial for advanced wireless communication systems.
• Gallium Nitride (GaN) is a key material for high-frequency applications.
• Developing strainable GaN devices on flexible substrates presents significant challenges.

Purpose of the Study:

• To demonstrate strainable, high-frequency radio-frequency (RF) GaN devices on flexible substrates for the first time.
• To investigate the impact of strain on the electrical and RF performance of AlGaN/GaN heterostructures.
• To enable conformal and highly integrated electronic materials for RF applications.

Main Methods:

• Epitaxial growth of AlGaN/GaN heterostructures on 2D boron nitride.
• Chemical-free transfer of GaN films to soft, flexible substrates.
• Uniaxial straining of transferred heterostructures up to 0.85% strain.
• Evaluation of electrical performance (electron mobility, sheet carrier density) and RF performance (cutoff frequency, maximum oscillation frequency).

Main Results:

• Achieved near state-of-the-art electrical performance with electron mobility > 2000 cm² V⁻¹ s⁻¹ and sheet carrier density > 1.07 × 10¹³ cm⁻².
• Demonstrated cutoff frequencies > 42 GHz and maximum oscillation frequencies > 74 GHz at up to 0.43% strain.
• Successfully fabricated strainable high-frequency RF GaN devices on flexible substrates.

Conclusions:

• Flexible GaN thin films enable strainable, conformal devices for efficient wireless communication.
• The developed method allows for chemical-free transfer and straining of GaN heterostructures.
• This work represents a significant advancement toward conformal, highly integrated electronic materials for RF applications.