研究目的
To improve the color purity of monolithic full color micro-LEDs using distributed Bragg reflector and blue light absorption material.
研究成果
The study successfully fabricated monolithic full color micro-LEDs with improved color purity using HBR and DBR structures. The output intensity of green and red QDs/micro-LEDs was increased by 11% and 10% with HBR, and further increased by 20% and 23% with DBR. The color purity was enhanced to 90.9% and 90.3% for green and red QDs/micro-LEDs, respectively, with the addition of a blue light absorption layer.
研究不足
The reflectivity of the DBR depends on the incident angle of the light, which may reduce its effectiveness if the light is not incident perpendicularly. The study also notes the potential for reabsorption of converted light by excessive QDs in the slurry.
1：Experimental Design and Method Selection:
The study used CdSe/ZnS core-shell quantum dots (QDs) as color conversion materials excited by GaN-based blue micro-LEDs. Hybrid Bragg reflector (HBR) and distributed Bragg reflector (DBR) were fabricated to reflect downward and non-absorbed blue light, respectively. A blue light absorption layer was deposited on the DBR to absorb escaped blue light.
2：Sample Selection and Data Sources:
CdSe/ZnS core-shell QDs with dimensions of 3 nm and 5 nm were purchased from Taiwan Nanocrystal Inc. GaN-based blue micro-LEDs epitaxial wafers were supported by Epistar Co.
3：List of Experimental Equipment and Materials:
Equipment included a metal organic chemical vapor deposition system, electron-beam evaporator, rapid temperature annealing (RTA) system, and UV–Visible spectrophotometer. Materials included CdSe/ZnS QDs, TiO2 and SiO2 granules, black photoresist, and blue light absorption material.
4：Experimental Procedures and Operational Workflow:
The process involved epitaxy of GaN-based micro-LEDs, deposition of HBR and DBR, filling QDs into openings, and depositing a blue light absorption layer.
5：Data Analysis Methods:
Electroluminescence (EL) spectra were measured using an Agilent 4156C semiconductor parameter analyzer and a spectrometer. Reflectivity and absorptivity spectra were measured using a UV–Visible spectrophotometer.
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