Analysis of efficiency limitations in high-power InGaN/GaN laser diodes

Twenty years after their first demonstration by Shuji Nakamura, InGaN/GaN lasers still exhibit less than 40 % electrical-to-optical power conversion efficiency. This paper investigates reasons behind the efficiency limitation by advanced numerical simulations of measured high-power laser characteristics. Auger recombination is identified as a major limitation at all power levels, but the inherently high series resistance becomes the most restrictive limitation at higher power. Since the traditional efficiency analysis method produces misleading results, we propose an alternative method that is also applicable without numerical simulation.