I. S. Romanov

On the effect of ballistic overflow on the temperature dependence of the quantum efficiency of InGaN/GaN multiple quantum well light-emitting diodes

The dependences of the quantum efficiency of InGaN/GaN multiple quantum well light-emitting diodes on the temperature and excitation level are studied. The experiment is performed for two luminescence excitation modes. A comparison of the results obtained during photo- and electroluminescence shows an additional (to the loss associated with Auger recombination) low-temperature loss in the high-density current region. This causes inversion of the temperature dependence of the quantum efficiency at temperatures lower than 220–300 K. Analysis shows that the loss is associated with electron leakage from the light-emitting-diode active region. The experimental data are explained using the ballistic-overflow model. The simulation results are in qualitative agreement with the experimental dependences of the quantum efficiency on temperature and current density.

Comparative analysis of efficiency droop in InGaN/GaN light- emitting diodes for electrical and optical pumping conditions

The analysis of efficiency droop in InGaN/GaN light-emitting diodes for electrical and optical pumping conditions is presented. Authors show that room temperature efficiency droop is well described by ABC-model for both pumping regimes. For low temperatures additional ballistic leakage should be considered to explain efficiency droop for the case of electrical pumping.

Effect of growth temperature of GaN:Mg layer on internal quantum efficiency of LED structures with InGaN/GaN quantum wells

The results of studies of quantum efficiencies for photoluminescence and electroluminescence regimes of blue light-emitting diode structures with InGaN/GaN quantum wells are presented. Experimental samples differed in growth temperature of p-GaN emitter layer. It is shown that increasing of growth temperature of p-GaN layer in temperature range 940-1060 °C leads to decreasing of internal quantum efficiency due to diffusion of magnesium atoms from p-GaN into quantum wells. At the electroluminescence regime quantum efficiency of samples with low temperature p-GaN is limited by insufficient crystal quality or low solubility of magnesium in emitter layer.