Study On High Luminous Eficicency GaN-based High-Voltage LED Devices

High voltage light-emitting diodes(HV-LED) with high voltage and low driving current can solve the reliability problem exits in the polycrystalline packaging process, and reduce the energy loss during the voltage conversion, so it become a hot topic at home and abroad. Based on the fabrication of Ga N-based HV-LED device, this paper is focus on the basic research of chip technology and optical properties of Ga N-based HV-LED, The detail contents of the study are as follow:To enhance the light output efficiency of Ga N-based high-voltage LED, four pair of Ti3O5/Si O2(100nm/40nm)distributed Bragg reflector(4-MDBR) and hybrid reflector including 4-MDBR and Al metal layer(600nm)(4-MDBR-Al) was fabricat-ed on the backside of sapphire substrate. At 20 m A injection current,the light-output power of HV-LED with 4-MDBR-Al is 294.4m W.Compared to 4-MDBR, the enhan-cement of light-output power induced by 4-MDBR-Al is 4.6%.The optics simulation is conducted on how to improve light power output of the side wall so as to enhance its light efficiency. The results show that chip shape of square or rectangular has better light output efficiency; The complex lateral structure of cicular has a better light output efficiency than others; Further analysis of the influence on light output efficiency by width of the isolation gap, the results show that without lateral microstructure,the largest value of light efficiency is at 30μm, while with lateral microstructure,it is at 50μm.To enhance optical properties of Ga N-based high-voltage LED,optimizing the width of the isolation gap between the chip of the light emitting units.This paper fabricated Ga N-based HV-LED with side microstructure and design four different isolation gap(10μm、20μm、30μm and 40μm). The experimental results show that with the isolation gap of 20μm,the electric and optical properties of the chip are the best, At 20 m A injection current, the forword voltage is 50.72 V, the light output power is 373.54 m W,and the electro-optical conversion efficiency is 36.83 %.Using mirror aluminum and ceramic substrate for COB package in the form of a series of four chip. The result show that the forword voltage, light output power, saturation optical power, sarturation current, light output efficiency, luminous decay,and the red shift of blue wavelength of HV-LED devices packaging with mirror aluminum substrate are all better than that of packaging with ceramic substrate. Under the injection current of 20 m A and the substrate temperature of 20℃, the forword voltage of HV-LED devices packaging with mirror aluminum substrate is 198.9V, and the light output efficiency is 122.2lm/W.