Temperature Droop Characteristics of Internal Efficiency in Quantum Well Light-Emitting Diodes

The temperature droop characteristics of internal efficiency (IE) in InGaN/GaN quantum well (QW) structures were investigated using the multiband effective mass theory. In the case of a relatively small Auger recombination (<; C_A = 5 × 10^-30 cm⁶s), the QW structure with a smaller In composition (x = 0.1) shows a larger hot/cold factor (IE_T1/IE_T2, with T₁ > T₂) than that with a larger In composition (x = 0.3) because the radiative recombination is dominant and the IE of the former is much larger than that of the latter. The hot/cold factors for QW structures with x = 0.1 and 0.3 are 0.85 and 0.71 at J = 100 A/cm², respectively. On the other hand, in the case of a relatively large Auger recombination (> C_A = 10^-28 cm⁶s), the hot/cold factor (0.69) of the QW structure with a larger In composition is found to be larger than that (0.62) with a smaller In composition. This is attributed to the fact that the Auger recombination is dominant even for the QW structure with a small In composition and that the difference of the IE between two different temperatures decreases with increasing x.