Analysis and Preparation of Novel Gan-based Light-Emitting Diode Chip |
|
Author | WangPei |
Tutor | LiuSheng;GanZhiYin |
School | Huazhong University of Science and Technology |
Course | Mechanical Manufacturing and Automation |
Keywords | GaN-based light-emitting diodes Optical modeling Current spreading The light extraction efficiency Electrode structure |
CLC | TN312.8 |
Type | PhD thesis |
Year | 2011 |
Downloads | 118 |
Quotes | 0 |
In recent years, with the development of the design level of semiconductor materials and devices and preparation techniques, the performance of the light emitting diode (LED) indicators rapid increase in the field of semiconductor lighting caused widespread attention and study, wherein the GaN-based high-power LED chip as a white LED lighting The core is to become a research hotspot. LED chip as optoelectronic devices, high luminous efficiency is the most fundamental goal. This article focused on the high-power GaN-based LED chip, conducted their study of the optical model, the electrical model, structural optimization and preparation process for the target to obtain high luminous efficiency. Firstly, the GaN-based LED chip optical modeling study, were studied Max Wei Quanbo electromagnetic field theory based finite element optical model and Monte Carlo ray tracing model based on the theory of geometrical optics. Electromagnetic finite element study of the optical propagation model discussed in the light-emitting unit, the absorbing boundary meshing and solving problems. Monte Carlo ray tracing model fitting and experimental test theoretical formula means the system analysis and summary of the various materials in the chip optical parameters such as refractive index and absorption coefficient through the ITO (Indium Tin Oxide) produced on the surface microstructure of the light extraction efficiency of the LED chip experimental results and the calculated results were compared to verify the accuracy and feasibility of the model. Modeling studies, the current expansion of the LED chip is then coupled electrical and thermal expansion model of a complete three-dimensional current research according to the basic theory of semiconductor physics and the theory of heat conduction, and discuss the basic equations and boundary conditions in the model, and two different electrode structure LED chip simulation results and the test results were compared to verify the feasibility of the model in the LED chip electrode structure optimization design. Optical model of the light extraction efficiency of the structure of several different LED chips comprehensive analysis and discussion of the current expansion model to analyze the impact of different electrode structure of the the chip current expansion and temperature distribution suits LED chip electrode structure design a few basic guidelines. Based on the analysis of the different structure of the LED chip light extraction efficiency and the current expansion, the paper proposes a new trench structure LED chip, and analysis of this structure in enhancing the the chip light extraction efficiency and improve current spreading performance advantages as well as with on the feasibility of large-size LED chip. Finally, the detailed process experiments several important processes in the new type of the trench structures LED chip preparation process. The selection and heat treatment process of a different alloy than the contact resistance of the p-type GaN ohmic contact, and found that 500 ° C annealing treatment can effectively reduce the specific contact resistivity. The dry etching of the GaN epitaxial layer of a more comprehensive process experiments to determine the parameters of the etching process, adapted to the LED chip preparation of the novel trench structure. Flow system was prepared by a standard LED chip and optically electrical characteristics testing of the new structure of the LED chip, it is found that the kind of structure of the LED chip than the ordinary structure of the LED chip in the optical power with the injection current to increase saturation characteristics has obvious advantages The structure has a lot of applications in oversized chip prospects.