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A method for preparing a quantum dot (QD)-white light-emitting diode (WLED) is reported. Holes were etched in the SiO2 layer deposited on the sapphire substrate of the flip-chip LED by inductively coupled plasma, and these holes were then filled with QDs. An ultraviolet-curable resin was then spin-coated on top of the QD-containing SiO2 layer, and the resin was cured to act as a protecting layer. The reflective sidewall structure minimized sidelight leakage. The fabrication of the QD-WLED is simple in preparation and compatible with traditional LED processes, which was the minimum size of the WLED chip-scale integrated package. InP/ZnS core-shell QDs were used as the converter in the WLED. A blue light-emitting diode with a flip-chip structure was used as the excitation source. The QD-WLED exhibited color temperatures from 5900 to 6400 K and Commission Internationale De L'Elcairage color coordinates from (0.315, 0.325) to (0.325, 0.317), under drive currents from 100 to 400 mA. The QD-WLED exhibited stable optoelectronic properties.

In this letter, we describe the design and fabrication of high-power AlGaN-based ultraviolet (UV) flip-chip high-voltage light-emitting diodes (LEDs) operating at 368 nm with an epitaxial indium tin oxide (ITO)/Al reflecting mirror and symmetry electrode layout. Metal-organic chemical vapor deposition (MOCVD) was used to grow an ITO thin film as a transparent electrode on the LED surface. At 365 nm, epitaxial ITO thin films exhibited a transmittance of up to 93.6%. Additionally, the epitaxial ITO/Al reflective mirror has a reflectance of 81.2% at 365-nm. To investigate the electrical characteristics, four types of HV-LED micro-cells were constructed with varying n-type mesa structures and p-type interconnect electrodes. We demonstrated a forward voltage (Vf) of 7.86 V at 350 mA with a 2 × 2 mico-cells high-voltage ultraviolet 368-nm flip-chip LED after optimising electrode structure and device process.

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AlGaN-Based flip-chip Ultraviolet Light-Emitting Diodes at 365 nm with epitaxial ITO transparent ohmic contact layers and Al reflective were fabricated. The epitaxial ITO thin film exhibits higher transmittance than that of sputter ITO at 365nm, which is 93.6% and 85%, respectively. The epitaxial ITO thin film is more suitable for 365nm UV-LED. And the reflectance of the ITO/Al layers is 81.2% at 365nm, much higher than that of the ITO/Ag layers, which is only 53.2% at 365nm. When the current injection is 350mA, the forward voltages are 3.43V and 4.05V for flip-chip UV-LED and conventional UV-LED, respectively. The forward voltages of flip-chip UV-LED is much lower than that of conventional UV-LED, because the series resistance (Rs) of the flip-chip UV-LED is 0.73 Ω, much lower than 2.98 Ω of conventional UV-LED. The flip-chip UV-LED with epitaxial ITO/Al reflective mirror and Symmetry Electrode arrangement is more suitable for high power application.