Glowing LED with silicon carbide crystal structures emitting warm white light.

Brighter Future: How New LED Tech Could Spark a Lighting Revolution

Rhea Morgan in Tech & Innovation September 2025 • 4 min read.

"Silicon Carbide and Hydrogen Silsesquioxane Bonding Create Efficient, Eco-Friendly Light"

In recent years, silicon carbide (SiC) has emerged as a highly sought-after industrial material, revolutionizing various applications ranging from waveguides and biosensors to the creation of innovative light-emitting diodes (LEDs). Renowned for its exceptional optical, thermal, and electrical characteristics, SiC has garnered considerable attention, especially for its potential in crafting white LEDs that are both efficient and sustainable.

Traditional white LEDs typically combine a GaN-based blue LED chip with yellow phosphors, such as cerium-doped yttrium aluminum garnets. However, the reliance on rare-earth elements and the degradation of phosphor performance pose significant limitations. As a compelling alternative, researchers have explored combining near-ultraviolet (NUV) LEDs with donor and acceptor co-doped SiC substrates, offering a path to white LEDs that eliminate the need for rare-earth elements. This innovative approach employs two adjacent fluorescent-SiC (f-SiC) epi-layers, strategically doped to convert wavelengths and create the desired light spectrum.

One promising method involves integrating the NUV LED and the f-SiC epi-layers through adhesive bonding, using an intermediate adhesive layer. This technique offers advantages like low bonding temperatures, tolerance to surface irregularities, resistance to stress and mechanical vibrations, and uniform load distribution across a broad area. The use of Hydrogen silsesquioxane (HSQ) is getting attention in the LED industry because its more transparent than other alternatives.

The Science Behind Hydrogen Silsesquioxane (HSQ) Bonding

Glowing LED with silicon carbide crystal structures emitting warm white light.

Adhesive bonding offers an attractive solution by applying flowable adhesives between surfaces, effectively smoothing out roughness and bringing atoms into sufficient proximity for van der Waals bonds to form. These bonds are essential for the adhesion process. Unlike fusion bonding, which demands extremely close contact and is challenging with rough surfaces, adhesive bonding is more adaptable and easier to implement.

However, for NUV LED applications, the adhesive material must exhibit high transparency in the near-ultraviolet range to maximize the excitation NUV light reaching the f-SiC epi-layers. This is where hydrogen silsesquioxane (HSQ) steps in.

High Transparency: HSQ boasts superior transparency in the NUV range compared to other materials like BCB or SU-8.
Versatility: HSQ is a commercially available inorganic compound used in various micro- and nano-engineering applications.
Multiple Uses: It functions as a high-resolution negative electron beam resist, a molding material in nanoimprint lithography, and a mask in dry etching processes.

The researchers conducted a detailed study on the adhesive bonding of a NUV LED to a free-standing f-SiC epi-layer using HSQ. By spinning HSQ layers onto both the NUV LED's 4H-SiC substrate and the polished backside of the f-SiC epi-layer, they created a seamless bond. The process involved controlled heating and vacuum conditions to ensure optimal adhesion.

The Future of Lighting is Here

The successful bonding of a NUV LED to a free-standing f-SiC epi-layer using HSQ demonstrates the potential of this adhesive bonding approach. The hybrid LED exhibited strong warm white emission, confirming the effectiveness of HSQ in SiC-based LED fabrication. With ongoing advancements in materials and techniques, the future holds even brighter prospects for efficient, sustainable, and high-performance LED lighting.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.mssp.2018.10.028, Alternate LINK

Title: An Adhesive Bonding Approach By Hydrogen Silsesquioxane For Silicon Carbide-Based Led Applications

Subject: Mechanical Engineering

Journal: Materials Science in Semiconductor Processing

Publisher: Elsevier BV

Authors: Li Lin, Yiyu Ou, Valdas Jokubavicius, Mikael Syväjärvi, Meng Liang, Zhiqiang Liu, Xiaoyan Yi, Philipp Schuh, Peter Wellmann, Berit Herstrøm, Flemming Jensen, Haiyan Ou

Published: 2019-03-01

Everything You Need To Know

What makes silicon carbide (SiC) a sought-after material in LED production and other industrial applications?

Silicon carbide (SiC) is an industrial material valued for its optical, thermal, and electrical properties. It's used in waveguides, biosensors, and light-emitting diodes (LEDs). SiC is explored as a substitute for rare-earth elements in white LEDs, offering a more sustainable and efficient approach. Researchers are combining near-ultraviolet (NUV) LEDs with donor and acceptor co-doped SiC substrates to achieve this.

How does hydrogen silsesquioxane (HSQ) enhance the bonding process in near-ultraviolet (NUV) LEDs, and why is it preferred over other materials?

Hydrogen silsesquioxane (HSQ) is used as an adhesive to bond a NUV LED to a fluorescent-SiC (f-SiC) epi-layer. It facilitates the formation of van der Waals bonds between surfaces, creating adhesion. It is useful in NUV LED applications because it is transparent in the near-ultraviolet range, maximizing the excitation NUV light reaching the f-SiC epi-layers. Alternatives like BCB or SU-8 don't offer the same transparency.

What are the drawbacks of traditional white LEDs, and how does using silicon carbide (SiC) address these issues?

Traditional white LEDs commonly combine a GaN-based blue LED chip with yellow phosphors, such as cerium-doped yttrium aluminum garnets. This method relies on rare-earth elements, and the phosphor performance degrades over time, which poses limitations to the process. The use of NUV LEDs with donor and acceptor co-doped silicon carbide (SiC) substrates avoids the use of these elements, leading to a more sustainable solution.

What are the potential long-term impacts of using hydrogen silsesquioxane (HSQ) bonding in silicon carbide (SiC) LEDs on the lighting industry?

The future implications of using hydrogen silsesquioxane (HSQ) bonding in silicon carbide (SiC)-based LEDs could lead to more efficient, sustainable, and high-performance LED lighting. Its use in bonding NUV LEDs to f-SiC epi-layers enables the production of hybrid LEDs with strong warm white emission. Continued advancements could yield widespread adoption of this method, reducing our reliance on rare-earth elements and improving LED longevity and performance.

Besides adhesive bonding, what are some other applications of hydrogen silsesquioxane (HSQ) in micro- and nano-engineering?

Hydrogen silsesquioxane (HSQ) is commercially available inorganic compound and can be used for high-resolution negative electron beam resist, a molding material in nanoimprint lithography, and a mask in dry etching processes. It has high transparency and is used as an intermediate layer between the NUV LED's 4H-SiC substrate and the polished backside of the f-SiC epi-layer to create a strong warm white emission.