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Thermal and non-thermal saturation effects in the output characteristic of UV-to-violet emitting (AlGaIn)N LEDs

Thermische und nicht-thermische Sättigungseffekte in der Ausgangsleistung von UV-Violett emittierenden (AlGaIn)N LEDs
: Baeumler, M.; Kunzer, M.; Schmidt, R.; Liu, S.; Pletschen, W.; Schlotter, P.; Köhler, K.; Kaufmann, U.; Wagner, J.


Physica status solidi. A 204 (2007), No.4, pp.1018-1024
ISSN: 0031-8965
ISSN: 1862-6300
ISSN: 1521-396X
ISSN: 1862-6319
Journal Article
Fraunhofer IAF ()
InGaN/AlGaN; thermal roll-over; thermisches Überrollen; temperature coefficient; Temperaturkoeffizient; non-thermal roll-over; nicht-thermisches Überrollen; quantum efficiency; Quanteneffizienz; light emitting diode; Leuchtdiode

UV-to-violet emitting (AlGaln)N LEDs have been investigated with respect to the temperature-dependence of the output power characteristics and non-thermal rollover of the quantum efficiency at higher current densities. Analyzing MOVPE grown LED chips emitting in the 377 to 428 run wavelength interval, the temperature sensitivity was found to increase and the output power to decrease with decreasing wavelength lambda for lambda < 400 nm. A sub-linear increase of the output power with increasing injection current even in the absence of any thermal effects, i.e. a non-thermal rollover of the quantum efficiency, was observed to be most pronounced for longer wavelength LEDs (lambda > 400 nm). Furthermore, the transient temperature rise after turn-on has been studied for differently packaged 377 nm LEDs, for which the temperature coefficient of the output power has been found to be particularly large.