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Wafer Scale III-Nitride Deep-Ultraviolet Vertical-Cavity Surface-Emitting Lasers Featuring Nanometer-Class Control of
Chen Ji1, Jiaming Wang1,2, Fujun Xu1
1State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing, China.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|December 21, 2025
Summary
This study presents a novel strategy for deep-ultraviolet vertical-cavity surface-emitting lasers (DUV VCSELs) achieving nanometer-level cavity length control across a 4-inch wafer. This minimizes detuning and improves device performance for applications like atomic clocks.
Area of Science:
- Optoelectronics and Photonics
- Semiconductor Materials Science
- Nanotechnology
Background:
- AlGaN-based deep-ultraviolet vertical-cavity surface-emitting lasers (DUV VCSELs) are crucial for applications like optical atomic clocks and maskless photolithography.
- Device performance is significantly hindered by cavity length variations leading to resonance wavelength and gain peak detuning.
Purpose of the Study:
- To propose and demonstrate a DUV-VCSEL fabrication strategy enabling uniform nanometer-class control of cavity length over a 4-inch wafer.
- To minimize detuning issues by accurately controlling cavity length through epitaxy rather than fabrication processes.
Main Methods:
- A wafer-scale laser lift-off process to remove sapphire substrates from GaN templates, creating space for dielectric distributed Bragg reflector (DBR) deposition.
- Achieving a sharp GaN/AlGaN interface with an 80% Al composition difference to enable self-terminated etching with a 100:1 selectivity.
- Fabrication of 285.6-nm optically pumped DUV VCSELs utilizing double dielectric DBRs.
Main Results:
- Demonstrated nanometer-class control of cavity length uniformity across a 4-inch wafer, with a variation of only 0.81% (1.9 nm wavelength variation).
- Fabricated DUV VCSELs achieved a record low threshold power density of 0.38 MW cm-2.
- The fabricated devices exhibited a narrow linewidth of 0.11 nm.
Conclusions:
- The proposed DUV-VCSEL strategy effectively addresses cavity length detuning issues through precise epitaxial control.
- This approach enables wafer-scale fabrication of high-performance DUV VCSELs with improved uniformity and reduced threshold.
- The results pave the way for advanced DUV optoelectronic devices in critical applications.
