Pushing the limits of non-radiative recombination suppression in GaAs/GaInP light-emitting diodes by doping profile engineering

Optimizing the efficiency of optoelectronic devices is challenging at low currents, even with high-quality materials, due to the dominance of non-radiative Shockley-Read-Hall recombination at low carrier densities. In this study, we nearly eliminate the typical non-radiative recombination current in a GaAs/GaInP double-heterojunction light-emitting diode (LED) by shifting the pn-junction 200 nm into the GaInP barrier layer on the n-side. This involves reducing the doping in the n-barrier to below the background p-type doping level to relocate the built-in electric field. As a result, the space charge recombination current with the ideality factor of two is strongly suppressed and remains concealed in our experimental dark current density-voltage measurements. The experimental results, coupled with our physics-based model, indicate the potential for considerable efficiency gains at current densities below ∼ 1 A/cm². The findings prompt to carefully optimize the doping profiles of high efficiency LEDs and to reconsider the validity of using dark saturation currents as a metric for their performance.