The multiple light scattering of nanoporous (NP) GaN was systematically studied and applied to the color downconversion for micro-light-emitting diode (LED) display applications. The transport mean free path (TMFP) in NP GaN is 660 nm at 450 nm (light wavelength), and it decreases with a decreasing wavelength. It was observed that the short TMFP of the NP GaN increased the light extinction coefficient at 370 nm by 11 times. Colloidal QDs were loaded into a half 4″ wafer scale NP GaN, and 96 and 100% of light conversion efficiencies for green and red were achieved, respectively. By loading green and red QDs selectively into NP GaN mesas, we demonstrated the RGB microarrays based on the blue-violet pumping light with green and red color converting regions.

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In this study, CdSe/ZnS core-shell quantum dots (QDs) with various dimensions were used as the color conversion materials. QDs with dimensions of 3 nm and 5 nm were excited by gallium nitride (GaN)-based blue micro-light-emitting diodes (micro-LEDs) with a size of 30 μm × 30 μm to respectively form the green and red lights. The hybrid Bragg reflector (HBR) with high reflectivity at the regions of the blue, green, and red lights was fabricated on the bottom side of the micro-LEDs to reflect the downward light. This could enhance the intensity of the green and red lights for the green and red QDs/micro-LEDs to 11% and 10%. The distributed Bragg reflector (DBR) was fabricated on the QDs color conversion layers to reflect the non-absorbed blue light that was not absorbed by the QDs, which could increase the probability of the QDs excited by the reflected blue light. The blue light absorption material was deposited on the DBR to absorb the blue light that escaped from the DBR, which could enhance the color purity of the resulting green and red QDs/micro-LEDs to 90.9% and 90.3%, respectively.

The letter reports a theoretical and experimental study on the device performance of near ultraviolet light-emitting diodes ͑LEDs͒ with quaternary AlInGaN quantum barrier ͑QB͒. The indium mole fraction of AlInGaN QB could be enhanced as we increased the trimethylgallium flow rate. It was found the AlInGaN/InGaN LEDs can reduce forward voltage and improve light output power, compared with conventional GaN QB. By using advanced device simulation, it should be attributed to a reduction in lattice mismatch induced polarization mismatch in the active layer, which results in the suppression of electron overflow.

The FePt/Ti double layer films were prepared by dc magnetron sputtering on corning glass substrates with FePt and Ti targets. The Ti underlayer with 100-nm thickness was deposited at substrate temperature 200 C, and the FePt magnetic layer, 300 nm, was prepared at temperature from 200 C to 600 C for direct formation of ordered L1 0 FePt phase on the Ti underlayer. X-ray diffraction analysis showed that the [002] axis of Ti grain was perpendicular to the film plane and the FePt grains had a preferred growth of (111) plane parallel to the film plane. The degree of ordering of the FePt films increased as Ti underlayer was introduced. Magnetic property measurements indicated that the in-plane coercivities (Hc ) of the FePt/Ti films in which FePt films was deposited at different temperatures were all higher than that of FePt single layer film without Ti underlayer. When the deposition temperature of FePt film was fixed at 600 C, the Hc value of the FePt single layer film was 3.1 kOe, and it increased to 7.3 kOe as 100 nm Ti underlayer was introduced.