Ultrafast Laser-Induced Defects in β-Gallium Oxide Below Ablation Threshold
Emma DeAngelis1, Christopher Chae1, Sadikul Alam1
1Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, United States.
ACS Applied Materials & Interfaces
|January 5, 2026
Summary
Ultrafast laser pulses create subsurface defects in gallium oxide, forming amorphous layers and phase changes. These findings advance understanding of defect formation and precision material modification.
Area of Science:
- Materials Science
- Solid State Physics
- Nanotechnology
Background:
- Gallium oxide (Ga2O3) is a wide bandgap semiconductor with significant electronic and optical properties.
- Understanding laser-induced defects is crucial for controlled nanomaterial transformation.
- Defect formation mechanisms in Ga2O3 under ultrafast laser irradiation require detailed investigation.
Purpose of the Study:
- To investigate ultrafast laser-induced morphological and crystalline defects in (2̅01)β-Ga2O3.
- To explore the depth-dependent modification of Ga2O3.
- To understand the potential of ultrashort laser pulses for precision subsurface modification.
Main Methods:
- Irradiation of (2̅01)β-Ga2O3 with 95 fs, 1030 nm laser pulses.
- Kelvin probe force microscopy and depth-resolved cathodoluminescence spectroscopy (DRCLS).
- Scanning transmission electron microscopy (STEM) and FDTD simulations.
Main Results:
- Laser-induced subsurface crystallographic defects were detected below the ablation threshold.
- A depth-dependent modification was observed: amorphous layer, γ-Ga2O3 phase change, and point defect region.
- DRCLS probed depths of 58-180 nm, complemented by STEM for surface and near-surface analysis.
- FDTD simulations showed high carrier generation density consistent with experimental observations.
Conclusions:
- Ultrafast laser irradiation induces complex, depth-dependent defect structures in β-Ga2O3.
- These defects include amorphous layers, phase transformations, and point defect variations.
- The study highlights the potential of ultrashort laser pulses for precise subsurface engineering in wide bandgap semiconductors.
