III-Nitride MEMS drum resonators on flexible metal substrates

Area of Science:

• Materials Science
• Nanotechnology
• Mechanical Engineering

Background:

• III-Nitride (III-N) materials are crucial for microelectromechanical systems (MEMS) due to their unique electronic and mechanical properties.
• Fabricating III-N MEMS resonators on flexible substrates presents challenges in material transfer and maintaining structural integrity.

Purpose of the Study:

• To present a simple and efficient method for fabricating III-Nitride (III-N) mechanical resonators on flexible metal substrates.
• To demonstrate a Self-Lift-Off and Transfer (SLOT) process for creating crack-free III-N heterostructures on flexible platforms.
• To analyze the performance and mechanical properties of the fabricated III-N MEMS resonators.

Main Methods:

• Van der Waals epitaxy of III-N epilayers on a hexagonal-Boron Nitride (h-BN) release layer.
• Deposition of a thick metal stressor to initiate a one-step Self-Lift-Off and Transfer (SLOT) process.
• Local etching and electrode deposition to release self-standing III-N layers with integrated actuation.
• Characterization using optical profilometry, laser Doppler vibrometer, and Finite Element Method (FEM) simulations.

Main Results:

• Successfully transferred III-N heterostructures from sapphire growth wafers to flexible metal substrates using the SLOT process.
• Fabricated III-N MEMS drum resonators exhibiting static deflections and distinct vibration modes.
• FEM simulations provided insights into mechanical properties and estimated stress in the released GaN and AlGaN layers.
• Demonstrated a straightforward approach for cost-effective, flexible, and crack-free III-N MEMS resonators.

Conclusions:

• The developed SLOT process is a practical and efficient method for fabricating flexible III-N MEMS resonators.
• This technique enables the production of high-quality, crack-free III-N structures on versatile metal substrates.
• The fabricated resonators show promising characteristics for various MEMS applications requiring flexibility and robustness.