Conductive omni-directional reflectors for spontaneously emitting light sources

用于自发发射光源的导电全向反射器

• 批准号: 0401075
• 负责人: E. Schubert
• 金额: --
• 依托单位: Rensselaer Polytechnic Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-15 至 2007-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0401075&HistoricalAwards=false
• 关键词: Conductive; omni; directional; reflectors; spontaneously

0401075SchubertSpontaneously-emitting light sources based on semiconductors are used in applications as diverse as lighting, sensing, communications, and signage. The efficient extraction of light from the light-emitting material into free space is essential for the future advancement of such light sources. There are two fundamental approaches enabling efficient light extraction in spontaneous emitters, namely the employment of structures with near-perfect transparency or the employment of optical reflectors with near-perfect reflection characteristics. Such reflectors should reflect light with very low optical losses irrespective of the angle of incidence and wavelength. A question of great intellectual interest and technical relevance concerns the optimum type of reflector that meets these requirements.Here a novel type of reflector is proposed that possesses (i) high reflectivity, (ii) omni-directional characteristics, (iii) electrical conductivity, and (iv) broad spectral range. The reflector consists of a semiconductor, a low-refractive-index dielectric layer perforated by an array of micro-contacts, and a metal layer. It is shown that such a triple-layer omni-directional reflector (ODR) has reflectivities 99 % with a weak anglular dependence thereby significantly increasing the light-extraction efficiency in spontaneously-emitting sources. The new type of ODR compares very favorably with the well-known metal reflector and distributed Bragg reflector. The demonstration of performance improvements in GaInN and AlGaInP LEDs using the new ODR will be an integral part of the project. It is known that these LEDs suffer from low metal-contact reflectivity (GaInN LEDs) and the lack of reflectivity at oblique angles of incidence in distributed Bragg reflectors (AlGaInP LEDs).

0401075Schubert 基于半导体的自发光光源用于照明、传感、通信和标牌等多种应用。将光从发光材料有效地提取到自由空间对于此类光源的未来发展至关重要。有两种基本方法可以实现自发发射器中的有效光提取，即使用具有近乎完美透明度的结构或使用具有近乎完美反射特性的光学反射器。无论入射角和波长如何，此类反射器都应以非常低的光学损耗反射光。一个具有极大智力兴趣和技术相关性的问题涉及满足这些要求的最佳类型的反射器。这里提出了一种新型反射器，它具有（i）高反射率，（ii）全向特性，（iii）导电性， (iv) 宽光谱范围。反射器由半导体、微接触阵列穿孔的低折射率介电层和金属层组成。结果表明，这种三层全向反射器（ODR）的反射率高达 99％，并且角度依赖性较弱，从而显着提高了自发发射源的光提取效率。新型ODR与众所周知的金属反射器和分布式布拉格反射器相比非常具有优势。使用新的 ODR 来演示 GaInN 和 AlGaInP LED 的性能改进将是该项目的一个组成部分。众所周知，这些 LED 的金属接触反射率较低（GaInN LED），并且分布式布拉格反射器（AlGaInP LED）在斜入射角处缺乏反射率。