In the relentless pursuit of brighter, more efficient displays, researchers have long grappled with the challenges of creating red-emitting micro-LEDs on silicon substrates. Now, a groundbreaking study led by Hongyu Qin at the Institute of Next Generation Semiconductor Materials, Southeast University in Suzhou, China, offers a promising solution that could revolutionize the energy sector and beyond.
The study, published in the journal Crystals, focuses on the use of dielectric passivation layers to enhance the performance of InGaN red micro-LEDs on silicon substrates. These micro-LEDs, which promise superior brightness, energy efficiency, and thermal stability compared to traditional displays, have faced significant hurdles in their development. One of the most pressing issues has been the hydrogen-induced deactivation of p-GaN, a problem that arises during the growth of the SiO2 passivation layer via plasma-enhanced chemical vapor deposition (PECVD).
Qin and his team systematically investigated the use of high-density metal-oxide dielectric passivation layers, specifically Al2O3 and HfO2, deposited by atomic layer deposition (ALD). These layers effectively suppress hydrogen diffusion, preserving the activation of p-GaN and ensuring improved ohmic contact formation. “The passivation layers not only mitigate hydrogen-induced degradation but also enhance the overall reliability and efficiency of the devices,” Qin explained.
The researchers characterized the properties of the epitaxial layer and the cross-section morphology of the dielectric layer using photoluminescence (PL) and scanning electron microscopy (SEM). Their findings revealed that Al2O3 exhibited superior thermal stability and lower current leakage under high-temperature annealing, while HfO2 achieved higher light-output power (LOP) and efficiency under increased current densities.
Electroluminescence (EL) measurements confirmed that the passivation strategy maintained the intrinsic optical properties of the epitaxial wafer with minimal impact on peak wavelength (Wp) and full width at half maximum (FWHM) across varying process conditions. This consistency is crucial for the commercial viability of red micro-LEDs, as it ensures stable performance and color accuracy.
The implications of this research are far-reaching. As the demand for high-performance displays continues to surge, particularly in applications such as augmented reality (AR), virtual reality (VR), wearables, and automotive displays, the need for efficient and reliable red-emitting micro-LEDs becomes increasingly urgent. The energy sector stands to benefit significantly from these advancements, as more efficient displays translate to reduced power consumption and lower operational costs.
Moreover, the use of silicon substrates offers cost efficiency and scalability for large-area production, making it an attractive option for the semiconductor industry. By addressing the critical challenges associated with GaN-on-Si technology, Qin’s research paves the way for the development of next-generation display technologies that are not only more efficient but also more environmentally friendly.
The study’s findings suggest that the proposed ALD dielectric passivation approach could address one of the bottlenecks in GaN-on-Si red micro-LED fabrication. As the technology matures, we can expect to see more widespread adoption of these advanced passivation techniques, leading to significant improvements in device performance and reliability.
In the words of Qin, “Our work demonstrates the efficacy of metal-oxide dielectric passivation in overcoming the challenges in InGaN red micro-LED on silicon substrate fabrication. We believe that these findings will contribute to the advancement of silicon-based GaN and red-emitting micro-LED technologies, offering scalable solutions for next-generation optoelectronic applications.”
As the energy sector continues to evolve, the integration of these advanced materials and techniques will be crucial in meeting the growing demand for high-performance, energy-efficient displays. The research led by Hongyu Qin and his team at Southeast University represents a significant step forward in this direction, offering a glimpse into the future of display technologies and their potential impact on the energy landscape.
