1.2-kV Vertical GaN PIN Rectifier With Ion-Implanted Floating Guard Rings

Breakdown characteristics analysis of kV-class vertical GaN PIN rectifiers by wafer-level sub-bandgap photoluminescence mapping

“…Nitrogen-implanted floating guard rings (FGRs), which have demonstrated effectiveness as an edge-termination technology for kV-class vertical GaN PIN rectifiers, can be used to improve the avalanche breakdown voltage and prevent device failure due to premature breakdown by creating a smooth electric potential and gradient electric field distribution along the junction interface as demonstrated in our previous study. 4,5 Besides the effects of the device edge-termination technique, material defects could also be a detrimental factor in device performance. Surface roughness can cause the incorporation of carbon-related defects and create a more insulating surface region than the bulk.…”

“…Details of the device fabrication process and electrical performance were reported in our previous study. 5 To analyze the impact of wafer quality on PIN rectifier breakdown characteristics, confocal PL microscopic mapping was performed at a sub-bandgap excitation wavelength of 405 nm (∼3.06 eV) in device locations prior to the individual PIN device fabrication. An illustration of the PL measurement setup is shown in Fig.…”

“…devices had 100 V higher averaged BV, indicating that the BV could be related to the number of defects within the device region. 18,19 The BV histograms of measured PIN rectifier devices on wafers A and B are shown in Fig. 3.…”

“…22,23 It has been reported that the existence of YL in all MOCVD-grown layers could be related to carbon impurities such as C N in n-GaN and undoped GaN 24 and nitrogen vacancy (V N ) in p-GaN:Mg. 25 In particular, the latter exhibits a PL band with a maximum near 2.33 eV or green luminescence (GL). 22 From the temperature-dependent J-V measurements and fitting for the Poole-Frenkel model reported in the previous study, 5 a trap state with an energy level of 0.53 ± 0.05 eV was extracted and can be related to V N . Nevertheless, V N is not observed under PL in n-GaN due to its neutral charge state and it is also hard to observe in p-GaN due to its 3+ state.…”