Charge transfer processes related to deep levels in free standing n-GaN layer analyzed by above and sub-bandgap energy excitation

Abstract

Charge transfer processes via deep levels (DLs) of a free-standing n-GaN grown by hydride vapor phase epitaxy is investigated using two types of excitations in time resolved photoluminescence (PL) analysis: above the bandgap energy (E g ) (AEG) and sub-E g (SEG). Using SEG excitation allowing us the PL observation free from carrier dynamics around band-edges such as excitonic recombination varying the population influx to DLs, intrinsic properties of DL-related PL and charge transfer processes are exhibited. The shortening of PL lifetime of red-light luminescence accompanied by a slight increase in its intensity by increasing temperature suggests the dominance of radiative transition.

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

“…Unlike the above-bandgap excitation, sub-bandgap PL selectively excites deep levels in GaN materials. 21 Integrated PL intensity within each device active area under 405 nm excitation of the device active region is plotted in Fig. 7(b), which indicates that the lower BV might be related to defects associated with high sub-bandgap PL intensity, as all macro-defect-free devices with BV below 1 kV reveal high integrated sub-bandgap emission intensities above 2000 arb.…”