Electroluminescence efficiency of (1\,0\,1̄\,0) -oriented InGaN-based light-emitting diodes at low temperature

This paper discusses radiative recombination efficiency in electroluminescence of InGaN-based light-emitting diodes prepared on the (1?0??0) plane. Radiative efficiency was studied over a wide range of temperatures and drive currents on four types of LED samples with different InGaN active-layer thicknesses. Efficiency was minimally affected by active-layer thickness, yet was a strong function of temperature and current. Efficiency reduction at high current was observed on these LEDs, which confirms strain-induced electric polarization fields are not a dominant mechanism. Luminescence intensity was found to be proportional to the square root of current at low temperature. Acceptor freeze-out was suggested to induce hole depletion at increased current; shortage of holes resulted in reduced efficiency and triggered off electron injection into the p-type layer to sustain total current. Injected electrons were shown to lead to the square-root relationship by solving rate equations.