A light emitting diode’s chip structure with low stress and high light extraction efficiency
Undesired residual stress always exists in light emitting diode (LED) after the process of metalorganic chemical vapor deposition (MOCVD) due to difference in thermal expansion coefficient of different layers, doping, and lattice mismatch. Residual stress would mostly induce defects in the process of LED chips, the packaging, accelerated testing and their applications. The influence of strain/stress on the optical properties of GaN based light emitting diode's (LED) chip is studied by molecular dynamic modeling. By simulation with finite element method (FEM), it is found that the stress caused by differences in thermal expansion coefficiency could be decreased by micro groove structures. The light extraction efficiency of LED chip could enhance with suitable micro structures.