InP/LiNbO₃ Covalent Heterointerface Construction via an Asymmetric Plasma Activation Strategy for Hybrid Integrated...

Area of Science:

• Materials Science
• Quantum Optics
• Integrated Photonics

Background:

• Lithium niobate (LiNbO3) is a promising material for complex integrated optical applications due to its optoelectronic properties.
• Existing methods struggle to integrate III-V semiconductors like Indium Phosphide (InP) with LiNbO3 for on-chip light sources, primarily due to thermal expansion mismatches.
• The inability of LiNbO3 to generate single photons necessitates hybrid approaches for quantum applications.

Purpose of the Study:

• To demonstrate a robust covalent heterointerface between Indium Phosphide (InP) and Lithium Niobate (LiNbO3).
• To overcome the thermal expansion mismatch challenge in InP/LiNbO3 integration.
• To enable the development of ultracompact on-chip light sources for classical and quantum photonic applications.

Main Methods:

• An asymmetric plasma activation strategy was employed, using different plasmas for InP and LiNbO3 activation to optimize surface functionalization and minimize defects.
• Ammonia solution was introduced to enhance the effectiveness of surface hydroxyl groups on LiNbO3, facilitating covalent bond formation.
• Surface characterizations and interface performance tests were conducted to evaluate the bonding strength and stability.

Main Results:

• A robust covalent InP/LiNbO3 heterointerface was successfully formed at 80 °C.
• The interface exhibited an enhanced bonding strength of 9.7 MPa.
• A hybrid quantum photonic chip was designed, demonstrating the platform's potential for efficient light coupling and misalignment tolerance.

Conclusions:

• The developed asymmetric plasma activation strategy effectively creates a stable covalent InP/LiNbO3 interface, overcoming thermal expansion challenges.
• This method provides a feasible pathway for integrating InP and LiNbO3, enabling ultracompact on-chip light sources.
• The InP/LiNbO3 platform shows significant potential for advancing hybrid integrated quantum systems and classical optoelectronics.