Study of InAlGaN/GaN HEMT structures by DLTFS with optical excitation

This paper deals with identifying electrically active defects and determining their fundamental parameters in InAlGaN/GaN HEMT structures by Deep Level Transient Fourier Spectroscopy (DLTFS) with optical excitation. Parameters of 5 electron-like defects and three hole-like defects were confirmed by DLTFS method. Parameters of 9 hole-like defects common to both structures were identified by DLTFS-O. Two hole-like defects were confirmed by both methods: DLTFS and DLTFS-O methods. The probable origin of electron-like defects could be nitrogen vacancies, defect clusters along screw- and mixed-type dislocations, the presence of surface states or emissions from the interface. The probable origin of hole-like defects could be the presence of surface states or defects in barriers. The benefits of different method utilization were confirmed by experimental results.