High external quantum efficiency of planar semiconductor structures
We have measured a very high photoluminescence external quantum efficiency (EQE) of 92% for a GaAs/GaInP double heterostructure mounted on a planar substrate. The measurement was made using a system we developed for accurately measuring the external quantum efficiency of highly radiatively efficient structures. The technique involves measuring uncalibrated photoluminescence and thermal signals from an optically pumped structure, as a function of incident laser power. The ac measurement technique allows the direct measurement of microkelvin temperature differences at room temperature, and also allows the Auger coefficient for intrinsic GaAs to be determined at relatively low injection levels.