In-situ spectroscopic analysis of the recombination kinetics in UVB LEDs during their operation

Abstract

The recombination kinetics in the quantum well (QW) active region of ultraviolet light emitting diodes have been measured in situ during device operation. Non-radiative recombination is enhanced with increasing operation time. Saturation effects allow us to estimate that the density of non-radiative recombination centers in the QW layers increases by ∼5 × 1015 cm-3 after operation. Corresponding defects are proposed to be present in the pristine device already. The recombination kinetics after optical excitation can be controlled by an additionally applied DC. The experimental approach allows the direct comparison and quantification of the effects of optically and electrically generated non-equilibrium carriers on the QW luminescence.