This thesis offers different methods for the characterization of traps at the AlGaN/dielectric interface in GaN–based devices, that can be used to extend our knowledge about such defects. For example, further experiments on various test structures fabricated with different process treatments, together with physical–chemical investigations, would be helpful to understand the elements involved in the creation and the passivation of the trap states. This would constitute a step forward towards the identification of the root cause of these defects.
Furthermore, the results on the standard AlGaN/SiN interface can be complemented by additional measurements at lower temperatures and better time resolution. This would clarify whether the observed increase of density of traps around 0.1 eV is just the tail of a normal distribution.
Finally, the optical investigations have just been started during the final phase of this thesis. Further DLOS experiments and other combinations of electrical and optical excitation can be performed on any test structure with a suitable gate contact. With these techniques it is possible to study capture and emission events caused by the interaction of the system with phonons (non–radiative transitions), as well as with photons (optical transitions), thereby characterizing the electronic as well as the optical activation energy of the defects. In this way, it will be possible to achieve a complete picture of the charge exchange transitions taking place at the defect sites.