Vertical-Injection AlGaInP LEDs with n-AlGaInP Nanopillars Fabricated by Self-Assembled ITO-Based Nanodots

Abstract

The light output power of AlGaInP-based vertical-injection light-emitting diodes (VI-LEDs) can be enhanced significantly using n-AlGaInP nanopillars. n-AlGaInP nanopillars,~200 nm in diameter, were produced using SiO 2 nanopillars as an etching mask, which were fabricated from self-assembled tin-doped indium oxide (ITO)-based nanodots formed by the wet etching of as-deposited ITO films. The AlGaInP-based VI-LEDs with the n-AlGaInP nanopillars provided 25 % light output power enhancement compared to VI-LEDs with a surface-roughened n-AlGaInP because of the reduced total internal reflection by the nanopillars at the n-AlGaInP/air interface with a large refractive index difference of 1.9.

GaInP nanowire arrays for color conversion applications

“…Thus, one can expect a compromise in the design of the converter layer to promote efficient absorption (by minimizing reflection losses) of the incident light and efficient out-coupling of light emitted (by photoluminescence) from the converter. Micro-and nanostructures have already been used to improve either light absorption 47 or light extraction from semiconductor LEDs 48 , but less frequently optimizing both at the same time. Most of the studies concerning light extraction rely on experimental investigations, as rigorous simulation is time demanding and difficult to calibrate.…”

“…For such coatings semiconductor nanowire (NW) or nanopillar (NP) arrays are excellent candidates since they can be fabricated by growth or by conventional pattern transfer methods. In the recent years, NWs/NPs have been extensively investigated for specific optical properties and device applications, such as broadband anti-reflection 47,58 , solar cells 59,60 , visible LEDs 33,34,48,61 , photodetectors 62 , and second-harmonic generation (SHG) 25,63 . Although NW/NP arrays can provide efficient in-coupling of light, efficient light absorption, and enhanced light extraction (compared to planar films) they are much less investigated as color converters.…”

Nanopillar-Based Light Emitting Diodes

“…Ryu et al tested the functioning of AlGaInP-based LEDs with vertical injection geometry with n-AlGaInP nanopillars etched as well. These LEDs provided up to 25% power enhancement due to the reduction of internal reflection/refractive index between materials, which allows a greater critical angle for photons to escape through [13]. Similarly, Guo et al examined the use of inverted organic LEDs (IOLEDs) on plastic substrates, and tested the inclusion of molybdenum disulfide (MoS 2 ) with four experimental devices [14].…”