Injection level dependent luminescence characteristics of UV-violet emitting (AlGaIn)N LED structures

A series of (AlGaIn)N LEDs covering the 377 to 428 nm wavelength interval has been analyzed by pulsed electro- and temperature dependent photo-luminescence with respect to the carrier density dependence of the quantum efficiency and peak position. A non-thermal rollover of the quantum efficiency vs. current is observed for the LEDs with higher In content and longer wavelengths (lambda > 400 nm). The photoluminescence data reveal In induced band tails as well as the presence of a quantum confined stark effect. Both effects contribute to the observed non-thermal rollover.