The temperature and strain dependence of the polarization of the in-plane electroluminescence of (0001) orientated (In)(Al)GaN multiple quantum well light emitting diodes in the ultraviolet spectral range has been investigated. For light emitting diodes with emission wavelength shorter than 300 nm the transversal-electric polarized emission intensity increases relative to the transversal-magnetic emission with increasing temperature whereas it decreases for ultraviolet light emitting diodes with longer emission wavelength. This effect can be attributed to occupation of deeper valence bands with increasing temperature. In addition, strain also strongly influences the in-plane light polarization of near ultraviolet light emitting diodes. The transversal-magnetic polarized emission becomes more dominant with decreasing in-plane tensile strain of the InGaN/(In)(Al)GaN multiple quantum well active region.
Kolbe, T.; Knauer, A.; Chua, C. L.; Yang, Z.; Yang, Z.; Kueller, V.; Einfeldt, E.; Vogt, P.; Johnson, N. M.; Weyers, M.; Kneissl, M. Effect of temperature and strain on the optical polarization of (In)(Al)GaN ultraviolet light emitting diodes. Applied Physics Letters. 2011; 99 (26): 261105.