The Radial Effect for E1 and E3 Deep Traps Concentration in n-GaN Layers

In this paper, we report on the electrical properties of two commonly observed deep levels in n-GaN known as E1 (E-c = 0.25 eV) and E3 center (E-c = 0.55-0.6 eV). The defects analysis has been carried out with the use of deep level transient spectroscopy and Laplace deep level transient spectroscopy techniques, respectively. We have found that both E1 and E3 trap concentration strongly depends on the distance to the original wafer edge, which is called here the radial effect, and decreases by over two orders of magnitudes as the distance increases. Moreover, we speculate that both deep levels can be related to iron or its complexes.