Views: 0 Author: Site Editor Publish Time: 2025-08-18 Origin: Site
UV-C LEDs (deep ultraviolet light-emitting diodes) hold immense potential in fields such as medical sterilization, water purification, and air disinfection due to their efficient germicidal properties. However, challenges like low luminous efficiency, poor thermal management, and short lifespan have hindered their commercialization. Research indicates that chip structure design is critical to improving performance. Let’s dive into the intricacies of optimizing UV-C LED chip structures.
UV-C LEDs typically use AlGaN material systems. Electrons and holes recombine in quantum wells to emit deep ultraviolet light. Luminous efficiency depends on internal quantum efficiency (IQE) and light extraction efficiency (LEE). IQE is influenced by material quality and carrier recombination efficiency, while LEE is affected by chip structure, interface reflection, and packaging methods.
UV-C light (especially around 275 nm) is absorbed by microbial DNA, forming pyrimidine dimers that disrupt replication and transcription, achieving sterilization. This acts like a “molecular scissor,” precisely targeting and destroying microbial genetic material to prevent reproduction.
1.1 AlGaN Material Composition Control
Increasing the Al component shortens the emission wavelength but introduces lattice mismatch and defect density. Studies show that using an AlN buffer layer reduces dislocations, while a graded Al composition design mitigates stress, improving crystal quality.
1.2 Quantum Well (MQW) Optimization
Multi-quantum well structures enhance carrier confinement. Optimizing the well/barrier thickness ratio (e.g., 2 nm/8 nm) boosts radiative recombination, and strain compensation techniques reduce defects in quantum wells, improving IQE.
2.1 Transparent Conductive Layer (TCL)
Traditional Ni/Au electrodes absorb UV-C light significantly. Using ITO or Al reflective electrodes can enhance light extraction efficiency.
2.2 Micro/Nano-Structured Electrodes
Nanopatterned electrodes reduce light absorption, improving LEE and allowing more UV light to contribute to disinfection.
3.1 Substrate Materials
Sapphire substrates are cost-effective but have poor thermal conductivity, while AlN offers high thermal conductivity at a higher cost. Patterned sapphire substrates (PSS) reduce dislocations and enhance light extraction.
3.2 Heat Sink Design
Integrating diamond heat dissipation layers lowers junction temperature, extending device lifespan and ensuring stable operation during prolonged use.
4.1 Surface Roughening Technology
Wet or dry etching creates micro/nano structures to reduce total internal reflection losses, allowing more light to escape the chip surface.
4.2 Distributed Bragg Reflector (DBR)
Integrating high-reflectivity DBR at the chip’s bottom enhances UV-C light emission efficiency, further improving disinfection performance.
Optimization strategies yield significant performance improvements. For instance:
Using an AlN buffer layer increases external quantum efficiency (EQE) from ~15% to 25%, achieving a 3.5-log disinfection efficiency against Escherichia coli.
Nanopatterned electrodes boost EQE from ~5% to 8%, with a 4.0-log disinfection efficiency against Staphylococcus aureus.
Diamond heat sinks triple device lifespan while maintaining high disinfection efficiency.
The chip structure design of UV-C LEDs plays a decisive role in enhancing luminescence and disinfection performance. Optimizing epitaxial growth, quantum well structures, electrode design, and thermal management significantly improves EQE and reliability. In the future, novel material systems like BAlGaN or superlattice structures may reduce defect density. Integrated packaging combining optical lenses and thermal management technologies will enhance practical applications. Developing large-scale AlN substrate growth techniques could drive the mass commercialization of UV-C LEDs, better serving human health and quality of life.
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