Study On Micro AlGaInP-LED Arrays Device And Full-color Integration

As known the new generation of display lighting energy,LED(light emitting doide)has become a key light-emitting devices in many fields such as display,projection,medical lighting,military communications and so on.With the proposal on concept of micro-projection,micro-display,the research direction of the researchers is gradually moving from large scale towards micro-small size device fabrication.In recent years,the micro-miniaturization of the preparation on LED array is being studied by a large number of research groups at home and abroad.Such as John A.Rogers’ team of Northwestern University,the Lin Jingyu’s team of the United States Texas Polytechnic University,the Dawson team at the University of Leicester and Liu Zhaojun’s Team of Hong Kong University of Science and Technology.In this paper,the thermoelectric performance of AlGaInP based on MEMS is studied,the process preparation scheme is improved,the structure parameters of array devices are optimized,and the optical properties of array devices are improved.Due to the continuous upgrading of the use of demand,Full-Color micro LED micro array display devices,which can be used to make AR,VR display,LCD backlight,all-weather traffic display,LiFi light source,is paid more and more attention.Micro pixel unit,high pixel density and portable wear has been the Full-Color micro LED array is on the developed direction.The flexible Full-Color micro LED array device not only has the basic features of the planar array device,but also can be arbitrarily curved,which further expands the application range of the Full-Color micro LED array device.As the influence of the electrode wire,the Full-Color micro LED array is difficult to reach the high pixel density by using COB process presently.In this paper,a flexible full-color micro led array fabrication process based on MEMS technology is proposed and studied,the feasibility of the process is validated.The specific work of this thesis can be divided into the following four parts:1.Dividing the large pixel size 500μm×500μm chip into small pixel element array,keeping the pitch 25μm,the result shows that the photoelectric performance of the array pixel element is improved and the modulation bandwidth is enhanced.LED arrays with pixel numbers of 3×3,4×4,and 5×5 have been studied in order to enhance the optical output power and decrease heat dissipation of an AlGaInP-based light emitting diode display device(pixel size of 280 μm×280 μm)fabricated by micro-opto-electro-mechanical systems.Simulation results show that the thermal resistance of the 3×3 array was 52.8 K/W and that the thermal resistance increased to 70.6 K/W for a 4×4 array and 86.6 K/W for a 5×5 array.The junction temperature was calculated by the peak wavelength shift method.The junction temperature of the center pixel is maximum owing to thermal crosstalk from neighboring pixels.The central pixel had a minimum value of temperature with 40 μm pixel pitch and 150 μm substrate thickness as calculated using thermal modelling using finite element analysis.The modelling was helpful to optimize the parameters of the highly integrated AlGa InP-based LED array fabricated by micro-opto-electro-mechanical systems technology.2.The effect of electrode structure on the photoelectric properties of LED devices is analyzed by finite element method.Comparison of two kinds of pixel segmentation method-ICP etching method and mechanical dicing method;Finally,the AlGaInP based led array device with pixel size 80μm×80μm and pitch 20μm is tested and analyzed,the results show that thinning substrate is advantageous to reduce the resistor of device and improve optical output power of pixel unit.3.By using the temperature controll transfer printing method,the LED array on the blue film surface can be transferred directly to the drive circuit board.Comparison the photoelectric performance of the LED device before and after the transfer printing,the reasonable working range of the chip is confirmed between 10 m A-20 mA,if continuing to increase the injection current,the energy utilization efficiency of the chip will be decreased.Fabricate and test the flexible bending LED array devices.Optimise the temperature control system of the transfer platform to simplify the preparation process.