Current-induced degradation process in (In)AlGaN-based deep-UV light-emitting diode fabricated on AlN/sapphire template

Abstract A comprehensive analysis of the degradation behavior of (In)AlGaN-based deep-ultraviolet light-emitting diode (DUV LED) stressed at a constant dc current of 60 mA has been presented. This work is based on combined X-ray diffraction (XRD), atomic force microscopy (AFM), electroluminescence (EL), cathodoluminescence (CL), current-voltage (I–V) and capacitance-voltage (C–V) characteristics. We used XRD and AFM data to investigate the structural properties of the epilayer. The EL spectrum shows two clear emission peaks at around 4.71 and 3.77 eV and a plateau region within 4.24 to 3.82 eV. To know the origin of the plateau region and the peak at 3.77 eV, we performed CL measurement. As a consequence of constant current stress, we obtained the following results: (1) a gradual degradation in EL power due to increase of Shockley–Read–Hall (SRH) recombination and the generation of new point defects in the active region; (2) a significant improvement in the leakage current, that is attributed to the enhance in trap assisted tunneling; and (3) a strong increment in the device capacitance in both reverse and forward bias regions, that is ascribed to the improvement in the net charge concentration and their redistribution in the active region of the LED.