Zhang Shuo, Liang Meng, Yan Yan, Huang Jinpeng, Li Yan, Feng Tao, Zhu Xueliang, Li Zhicong, Xu Chenke, Wang Junxi, Li Jinmin, Liu Zhiqiang, Yi Xiaoyan
Research and Development Center for Solid State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
Nanomaterials (Basel). 2022 May 11;12(10):1638. doi: 10.3390/nano12101638.
Constant advance in improving the luminous efficacy () of nitride-based light-emitting diodes (LEDs) plays a critical role for saving measurable amounts of energy. Further development is motivated to approach the efficiency limit for this material system while reducing the costs. In this work, strategies of using thin AlN prebuffer and transitional-refraction-index patterned sapphire substrate (TPSS) were proposed, which pushed up the efficiency of white LEDs (WLEDs). The AlN prebuffer was obtained through physical vapor deposition (PVD) method and TPSS was fabricated by dry-etched periodic silica arrays covered on sapphire. Devices in mass production confirmed that PVD AlN prebuffer was able to improve the light output power () of blue LEDs (BLEDs) by 2.53% while increasing the productivity by ~8% through shortening the growth time. Additionally, BLEDs on TPSS exhibited an enhanced top of 5.65% in contrast to BLEDs on the conventional PSS through Monte Carlo ray-tracing simulation. Consequently, of BLEDs was experimentally enhanced by 10% at an injected current density () of 40 A/cm. A peak of 295.2 lm/W at a of 0.9 A/cm and the representative of 282.4 lm/W at a of 5.6 A/cm for phosphor-converted WLEDs were achieved at a correlated color temperature of 4592 K.
提高氮化物基发光二极管（LED）的发光效率（）的不断进步对于节省可观的能源量起着关键作用。进一步的发展旨在接近这种材料系统的效率极限，同时降低成本。在这项工作中，提出了使用薄AlN预缓冲层和渐变折射率图案化蓝宝石衬底（TPSS）的策略，这提高了白光LED（WLED）的效率。AlN预缓冲层通过物理气相沉积（PVD）方法获得，TPSS由覆盖在蓝宝石上的干法蚀刻周期性二氧化硅阵列制成。大规模生产的器件证实，PVD AlN预缓冲层能够将蓝色LED（BLED）的光输出功率（）提高2.53%，同时通过缩短生长时间将生产率提高约8%。此外，通过蒙特卡罗光线追踪模拟，与传统PSS上的BLED相比，TPSS上的BLED顶部增强了5.65%。因此，在注入电流密度（）为40 A/cm²时，BLED的实验增强了10%。在相关色温为4592 K时，磷光转换WLED在0.9 A/cm²的电流密度下实现了295.2 lm/W的峰值发光效率（），在5.6 A/cm²的电流密度下实现了282.4 lm/W的代表性发光效率（）。
