Investigation of AlGaN/GaN Schottky structures by deep level fourier transient spectroscopy with optical excitation

This paper highlights electrical characterization of Schottky structures prepared on AlGaN/GaN designed for HEMT's using Deep Level Transient Fourier Spectroscopy (DLTFS) method with electrical and optical excitation. In case of electrical excitation the density of minority and majority carrier traps had strong effect on the evaluation, whereas preliminary DLTFS with optical excitation (MCDLTFS) measurements made possible to identify minority carrier defects with higher precision. Parameters of two electron-like defects EL1 (0.47 eV), EL2 (0.54 eV) and three hole-like defects HL1 (1.13 eV), HL2 (0.93 eV) and HL3 (0.49 eV) were identified. HL1 andHL2 were confirmed by both methods: DLTFS and MCDLTFS. These are connected to a Carbon interstitial defect and well-know threading dislocations. Experimental results confirmed the benefits of different method utilizations in complex defect identifications.