Influence of internal absorption and interference on the optical efficiency of thin-film GaN-InGaN light-emitting diodes

We present a first-principle method for quantitative modeling of optical energy flow and dissipation in thin-film (TF) light-emitting diodes (LEDs) based on highly general Green's function method. Unlike conventional models, the presented model simultaneously accounts for interference, near-field effects, and internal absorption in determining the radiance generated by a LED. We show that these effects have a profound influence on the efficiency of LEDs and strongly affect the light extraction efficiency (LEE) and the internal quantum efficiency. According to our results, the LEE of an InGaN-GaN TF-LED with untextured surfaces and typical active region (AR) thickness on the order of 10 nm is 67% while a LED with a thin AR exhibits only a LEE of 29%. Based on the numerical results, we discuss the factors that affect the overall efficiency and design considerations to optimize the structure of thin-film LEDs. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4798326]