The high-power LED market is experiencing rapid growth, driven by the increasing demand for energy-efficient lighting solutions. These advanced devices are particularly beneficial in industrial applications where efficiency plays a crucial role. The higher the efficiency of an LED, the less heat it generates, which simplifies and reduces the cost of thermal management. This makes high-efficiency LEDs not only more effective but also more economically viable in the long run.
In response to the evolving demands of the LED industry, many chip manufacturers are focusing on improving the efficiency of their products. Even small improvements in efficiency can lead to significant advantages in terms of profitability and competitiveness. This is especially true in the high-power LED sector, where production of high-end chips contributes significantly to profit margins.
Another key advantage of producing efficient LED equipment is its potential in the automotive lighting industry. High-efficiency and reliable LEDs have found success in headlight applications. However, they have struggled in general lighting, where low- and medium-efficiency LEDs dominate, causing financial difficulties for many manufacturers in this segment.
One of the most critical challenges in developing efficient LEDs is maximizing photon extraction. Due to the high refractive index of gallium nitride (GaN) compared to air, a large portion of the generated photons is trapped inside the device through total internal reflection. To overcome this issue, researchers often use patterned sapphire substrates. These surfaces help scatter light in multiple directions, increasing the chances of photons escaping from the chip.
The process involves etching patterns into a planar sapphire using a photoresist mask and inductively coupled plasma. This creates a dome-shaped surface that enhances light extraction. Some research groups have explored incorporating high-refractive-index contrast cavity structures into LEDs, which have shown promising results in improving light output. However, these techniques have yet to be widely adopted in mass production.
A notable contribution to cavity-based LEDs comes from a team at Seoul National University led by Euijoon Yoon. They developed nanoscale cavities using hollow silica nanospheres, which improved light extraction while reducing compressive stress in the surrounding GaN. This innovation allows for thinner sapphire wafers, lowering manufacturing costs. Despite these advances, there is still room for improvement, as the random placement and low density of the cavities limit their effectiveness.
To bridge the gap between lab-scale experiments and industrial production, South Korea's Hexa Solution has introduced a cavity sapphire substrate technology. Their process involves creating dome-shaped cavities through a combination of photoresist reflow, atomic layer deposition, and heat treatment. This method results in a highly scalable and robust production technique.
The unique optical properties of cavity sapphire substrates allow for enhanced light scattering and diffraction, leading to more vivid colors under different lighting conditions. Additionally, transmission experiments show that cavity sapphires offer better transmittance over a wide wavelength range than traditional patterned sapphires.
Simulation studies confirm that cavity sapphire substrates interact strongly with incoming light waves, effectively redirecting them and reducing total internal reflection. This leads to improved light extraction and overall performance in LEDs.
Performance tests comparing cavity sapphire and patterned sapphire substrates showed that LEDs made with cavity sapphire produced significantly higher optical power. At 240 mA, cavity sapphire LEDs emitted 40% more power and achieved peak emission at 468 nm. These results highlight the superior efficiency and performance of cavity sapphire technology.
Moreover, the production process for cavity sapphire substrates is more cost-effective and stable than traditional plasma etching methods. This makes it a more attractive option for mass production in the LED industry.
For more information, visit LEDinside’s official website or follow their WeChat public account. If you need to reproduce this content, please contact us via email and credit "from LEDinside." Unauthorized reproduction may result in legal action.
Audio Aux Cables,Type-C To 3.5Mm Audio Cable,3.5Mm Audio Adapter Cable,Type-C Audio Adapter Cable
ShenZhen Puchen Electronics Co., Ltd. , https://www.szpuchen.com