8 April 2022
Enkris releases Full Color GaN products and expands wafer size to 300mm for micro-LED applications
Enkris Semiconductor of Suzhou Industrial Park, China – which is a pure-play foundry for gallium nitride (GaN) epitaxial wafers for power electronics, micro-LED and UVC applications – has released its Full Color GaN® RGB series of products with wafer size up to 300mm for the micro-display industry.
GaN-on-Si LEDs show advantages over those grown on other substrates for micro-LED technology in terms of larger wafer size (200–300mm) and better surface quality. Furthermore, by taking advantage of state-of-the-art silicon processing in 200mm/300mm fabrication plants, high-performance arrays of tiny (5µm2) micro-LED pixels can be fabricated and integrated on a silicon CMOS driver with high yield.
Figure 1: Enkris’ Full Color GaN RGB series of products.
Near-eye-displays such as augmented reality (AR) and mixed reality (MR) devices require high-efficiency, ultra-fine-pitch (<5µm) red, green and blue pixels integrated on the same material platform. Indium gallium nitride (InGaN) materials can emit light efficiently, spanning the entire visible spectral range by adjusting the indium content. Although high-efficiency blue and green InGaN LEDs have been achieved, it is still very challenging to grow high-efficiency red LEDs due to the pronounced strain in the active region and the poor crystalline quality resulting from the large lattice mismatch between InGaN quantum wells (QWs) and GaN buffers. Enkris Semiconductor has successfully overcome these difficulties by using its patented strain engineering and polarization engineering (Figures 1 and 2). By adopting its unique bandgap tuning technology, Enkris has expanded its GaN-on-Si LED epiwafer product portfolio to the Full Color GaN RGB series of products (with wavelengths of 390-650nm) on 200mm silicon substrates.
Figure 2: IQE comparison and EL spectra of Full Color GaN RGB series of products on silicon and sapphire.
Wavelength uniformity is a key factor for micro-LED displays. Enkris says that its Full Color GaN RGB series has excellent wavelength uniformity across the whole 200mm wafer (Figure 3). Moreover, GaN-on-Si blue LED wafers are available up to 300mm in diameter, and the wavelength is reasonably good, with a standard deviation of less than 2nm (Figure 4).
Figure 3: Full Color GaN RGB series 200mm LED WLD mapping.
Figure 4: Enkris’ 300mm GaN-on-Si blue LED WLD mapping.
Enkris has also demonstrated RGB micro-LED arrays with a pixel size ranging from 2µm to 50µm, based on Full Color GaN RGB series of 200mm epiwafers (Figures 5 and 6). Thanks to the high-quality epiwafers, all the pixels can be lit up, even for each 2µm2 pixel (in a 100 x 100 array). This is the key accelerator for micro-display adoption, it is reckoned.
Figure 5: Enkris’ 200mm micro-LED wafer.
Figure 6: Micro-LED arrays based on Full Color GaN RGB series.
“For monolithic integration of micro-LEDs, it is a critical step to integrate all three colors into a single material platform of large-size GaN-on-Si,” says founder & CEO Dr Kai Cheng. “Our Full Color GaN series products will fulfil the industry’s requirement for AR/MR systems. In addition, the GaN-on-Si wafer size can be scaled up to 300mm, and we presented a 1200V 300mm GaN-on-Si platform in September 2021. The new platform of 300mm GaN-on-Si LEDs will show great promise in heterogeneous integration of GaN optical devices, GaN electronic devices and silicon devices,” he adds. “Enkris is now able to supply a true RGB GaN-on-Si epitaxial solution for the display industry and empower the development of full-color micro-displays.”
Enkris’s Full Color GaN series products are available on both GaN-on-Si and GaN-on-sapphire wafers.
Enkris Semiconductor expresses its gratitude to Raysolve for the support during device validation and evaluation of GaN epitaxial materials.