Unique correlations between the electrical and optical characteristics of InGaN/(In)GaN multiple quantum-well light-emitting diodes (LEDs) were investigated over a broad range of temperatures. The dependence of nonunity ideality factors extracted from. the current-voltage analysis on temperature determines the carrier-transport mechanisms in the heterodevices. The pseudotemperatures T-o for the LEDs with multiquantum barriers and with GaN barriers were found to be 945 and 1385 K, respectively, at temperatures of 180-300 K while having values of 1195 and 2720 K below about 180 K. Correspondingly, the temperature-dependent electroluminescence observations suggest that the T-o anomaly caused the spectral intensity to deteriorate. (c) 2006 American Vacuum Society.