Project Info

Project Goals and Description:

This project aims to develop a finely tuned inductively coupled plasma reactive ion etching (ICP-RIE) process for the fabrication of nanoscale patterns and metasurfaces on gallium nitride (GaN) materials. GaN's exceptional electrical, optical, and mechanical properties make it a prime candidate for advanced photonics, quantum devices, and optoelectronic metasurfaces. However, its chemical inertness and physical robustness pose significant challenges for achieving high-aspect-ratio, low-damage nanopatterning. Objectives:

• Optimize ICP-RIE parameters (e.g., gas chemistry, RF bias power, ICP power, pressure, and temperature) to achieve anisotropic, smooth-sidewall etching of GaN.

• Minimize surface roughness and plasma-induced damage to maintain GaN's optical quality post-etching.

• Demonstrate reproducible fabrication of nanopatterns and metasurfaces with feature sizes down to sub-100 nm.

Technical Approach:

• Mask Preparation: The student will be working with existing masks developed using electron beam lithography (EBL) or nano-imprinted patterns on GaN. A robust etch mask (e.g., Ni, SiO₂, or hard mask layers) will be deposited to improve etch selectivity and mask durability.

• Etch Chemistry: Chlorine-based gases (Cl₂, BCl₃, Ar) will be explored for their effectiveness in chemically assisted physical etching of GaN. Oxygen will be introduced in small amounts when needed to suppress polymer formation.

• Characterization:

  • SEM and AFM for feature inspection and sidewall roughness measurement.

  • Optical measurements (e.g., reflectometry) for assessing metasurface functionality.

Expected Outcomes:

• A reproducible ICP-RIE recipe for GaN etching with vertical profiles, low roughness (< 5 nm RMS), and high selectivity (> 5:1 mask-to-GaN).

• Successful fabrication of functional GaN metasurfaces demonstrating beam shaping, color filtering, or polarization control.

Impact:
This project will enable scalable manufacturing of GaN-based metasurfaces for high-performance optical applications, including advanced photonic circuits, quantum light sources, and next-generation displays.

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