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Reduced nonthermal rollover of wide-well GaInN light-emitting diodes

Reduziertes nicht-thermisches Überrollen bei GaInN Leuchtdioden mit breiten Quantentrögen
: Maier, M.; Köhler, K.; Kunzer, M.; Pletschen, W.; Wagner, J.


Applied Physics Letters 94 (2009), Nr.4, Art. 041103, 3 S.
ISSN: 0003-6951
ISSN: 1077-3118
Fraunhofer IAF ()
light emitting diode; Leuchtdiode; droop; non-thermal roll-over; nicht-thermisches Überrollen; freestanding GaN; freistehendes GaN; double heterostructure; doppelte Heterostruktur

Nonthermal rollover (or efficiency droop) of the electroluminescence (EL) efficiency has been investigated for near-UV-emitting (AlGaIn)N single-well light-emitting diodes (LED) with varying GaInN well widths grown on substrates with different dislocation densities (DDs). For each DD the well width of the mesa-LEDs has been optimized for maximum EL efficiency at high operating currents. LEDs on freestanding GaN (DD 4 x 10(exp 7) cm-2) with an 18 nm thick GaInN wide-well active region show the highest efficiency, and the output power-versus-current characteristic remains linear up to the highest pulsed current density of 750 A/cm2. In contrast, LEDs on sapphire grown with conventional low-temperature nucleation (DD 10(exp 9) cm-2) exhibit the optimum well width a 3 nm and show significant nonthermal rollover.