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.