Simulation of Highly Reflective GaN/Al _x Ga_1–x N Distributed Bragg Reflector Structure for UV-Blue LEDs

In this study, we showed theoretically enhanced reflectance characteristics of nitride based blue Light Emitting Diode (LED) by adding GaN/AlxGa_1–x N Distributed Bragg Reflector (DBR) between n-contact layer and GaN buffer layer. Calculation of reflectance and phase of electromagnetic waves are done by using Transfer Matrix Method (TMM). Light output of the LED structure is enhanced with 15 pair DBR, silver coating and optimizing GaN buffer, undoped GaN and n-contact GaN layer thicknesses. As a result of these, reflectance of the LED is increased from 92% to 98,6%. Finally, ∼5% enhancement is showed in reflectance of the blue LED which results in increase in output power of LED.