Design And Experiments Of LED Micro Arrays Based On AlGaInP

The device of LED micro-arrays is a two-dimensional array of ultra high brightness LEDs which are integrated on a chip with high density and micro size. Micro-light-emitting diode(micro-LED) arrays that can be used as optical switches and microdisplays in communication networks have attracted considerable attention in recent years. Because of their micro-scale size and energy-saving characteristics, micro-LED arrays can offer better current distribution, higher brightness, more uniform light output and faster response times than regular illumination or display devices.In this paper, a micro-LED array based on an Al Ga In P epitaxial wafer that was designed on the basis of a theoretical analysis is presented. Reliable Al Ga In P-based LEDs with high brightness are attractive devices because Al Ga In P has a direct energy bandgap in the visible spectrum in the yellow to red region Because the Al Ga In P lattice matches the Ga As substrate lattice well, the Al Ga In P epitaxial multilayers were grown on Si-doped n-Ga As substrates by metal-organic chemical vapor deposition. The epitaxial wafer included a Bragg reflector(DBR) layer, an Al Ga In P quantum well active layer, a current spreading layer(p-Ga P) and a contact layer(p+-Ga P).Through the design and experimental research of micro-arrays based on Al Ga In P-LED material, we completed the following work:1. An optimized structure of the device is designed. Each cells consist of light emitting unit and isolation groove trench, we have determined the width of isolation groove and calculated the area ratio of light outlet without considering the electrode shading effect. In contrast with different anode structures of single strip, double strip, square circle shape, the optimized square circle anode was choosen, and the size of the anode was fixed;2. The model of Al Ga In P-LED material was established, the thickness and the doping concentration of each layer in the model was fixed, the wavelength of the emergent light was 620 nm. The optimum operating voltage range of the device was determined according to the maximum of material internal quantum efficiency. Under the best device operating conditions, the light emitting unit with square circle anode was simulated, and we got the thermal power density and temperature distribution of each layer, then we obtained equivalent thermal resistance of the active layer to the external environment by calculating. Finally, a heat-sink structure which was suitable for this device was determined;3. The fabrication process of Al Ga In P-LED micro-array device based on MOEMS technology was designed. And the device was realized according to the experimental results and the integrated process. Finally, the device was tested.4. The structure of the flexible micro-LED was designed and flexible substrates were selected, and the fabrication process of flexible Al Ga In P-LED micro-array device based on MOEMS technology was designed.5. A 16×16 driving circuit was designed and fabricated based on STC89C52 single chip microcomputer. Then the Al Ga In P-LED micro-array device was tested, the I-V characteristic and P-I characteristic was got.