Single quantum well GaN/AlGaN UV LEDs defects investigation and modelization

The research work described in this thesis focused on the study of defects in GaN/AlGaN single quantum well UV-C LED structures. The study aimed to identify deep-level defects, their causes, and the consequences of their presence in LEDs. Furthermore, the behavior of the devices during and after accelerated life tests performed in temperature and current has been analyzed. Initially, the UV LEDs were characterized through current-voltage (I-V) and optical power-current (L-I) measurements, followed by voltage-dependent capacitance (C-V) measurements and advanced defect identification techniques such as Deep Level Optical Spectroscopy (DLOS). From the accelerated life tests, through electro-optical characterizations, it was possible to correlate the variations in device characteristics with the effects caused by defect generation, such as hydrogen diffusion into the active region and degradation of the p-type contact. With the data collected from the experimental measurements, an accurate electrical model of UV devices was implemented in a TCAD simulator, faithfully reproducing all the major parasitic effects.