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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. [ABSTRACT FROM AUTHOR]

In this letter, we report the impact of epitaxial Gd2O3 on the electrical properties of an AlGaN/GaN high electron mobility transistor (HEMT) grown on a 150 mm diameter Si (111) substrate. Incorporation of epitaxial Gd2O3 grown by the molecular beam epitaxy technique under a metal gate (metal/Gd2O3/AlGaN/GaN) causes six orders of magnitude reduction in gate leakage current compared to metal/AlGaN/GaN HEMT. We observe that epi-Gd2O3 undergoes complete structural changes from hexagonal to monoclinic as the thickness of the layer is increased from 2.8 nm to 15 nm. Such structural transformation is found to have a strong impact on electrical properties whereby the gate leakage current reaches its minimum value when the oxide thickness is 2.8 nm. We find a similar trend in the density of interface traps (Dit) having a minimum value of 2.98 × 1012 cm−2 eV−1 for the epioxide layer of thickness 2.8 nm. Our measurements also confirm a significant increase in the two dimensional electron gas (2DEG) density (∼40%) at AlGaN/GaN interface with epioxide grown on AlGaN, thus confirming the contribution of epitaxial lattice strain on 2DEG modulation. [ABSTRACT FROM AUTHOR]