Temperature-dependent electroluminescence anomalies influenced by injection current level in InGaN single-quantum-well diodes

Temperature dependence of the electroluminescence (EL) spectral intensity is investigated in the super-bright green InGaN single-quantum-well diode under low injection currents down to View the MathML source. It is found that a temperature-dependent variation pattern of the EL efficiency under very low and high injection currents shows a drastic difference. That is, when the current is low and thus the forward driving voltage is small, the EL intensity persists to increase with decreasing temperature due to the reduced nonradiative recombinations and the efficient carrier capture by the active region. On the other hand, when the injection current is high and the forward voltage is large, the EL intensity is significantly reduced at temperatures below View the MathML source. This unique EL efficiency variation pattern with temperature and current is explained by external field effects due to the driving forward bias in presence of internal (piezo and spontaneous polarization) fields.