Influence of negative-U centers related carrier dynamics on donor-acceptor-pair emission in fluorescent SiC

Abstract

E 1 /E 2 defects are the typical negative-U centers in n-type 6H silicon carbide (SiC). They are the main contributors to non-radiative recombination, which limits the carrier lifetime. In this study, two fluorescent 6H silicon carbide (f-SiC) samples and one bulk substrate were characterized via time-resolved photoluminescence (TRPL) and static photoluminescence (PL) measurements, where all the samples were nitrogen-boron co-doped 6H n-type. The existence of E 1 /E 2 defects, which caused the diminution of the internal quantum efficiency (IQE) and luminescence intensity of each sample, was confirmed by applying a carrier dynamics model based on negative-U centers. The carrier dynamics simulation reveals that the density of the E 1 /E 2 defects in bulk 6H SiC is two orders of magnitude higher than that of the f-SiC sample, causing much lower PL intensity in the bulk substrate compared to the two f-SiC samples. The IQE of the two f-SiC samples was extracted from the corresponding TRPL results, where the contrast between their IQE was further confirmed by the related PL measurement results. The slight difference in IQE between the two f-SiC samples was attributed to slightly different E 1 /E 2 defect concentrations. On the other hand, by implementing a steady-state donor-acceptor-pair (DAP) recombination calculation, it was found that the f-SiC sample with lower IQE had a higher DAP transition probability due to the higher doping level. This prompted further optimizations in the f-SiC crystal growth conditions in order to decrease the E 1 /E 2 defects while maintaining the correct doping parameters.

Photoluminescence Quantum Yield of Fluorescent Silicon Carbide Determined by an Integrating Sphere Setup

“…Compared to F-1, F-2/3 have slower PL decay at the initial stage. This indicates that the lifetimes, τ, corresponding to the decay channels of E 1 / E 2 centers, which have been confirmed as the dominating intrinsic defects in 6H f-SiC, in F-2/3 are longer. Assuming that these three samples have the identical hole capture cross sections (σ h ) corresponding to the E 1 / E 2 centers, the densities of E 1 / E 2 centers can be estimated by N = (σ h ⟨ν th,h ⟩τ) −1 , where ⟨ν th,h ⟩ refers to the mean thermal velocity of nonequilibrium holes.…”

Defect engineering using microwave processing in SiC and GaAs

“…It should be noted that a divacancy is a typical defect in 6H-SiC [20,45]. On the other hand, the level E c − 0.39 eV is more often associated with center E1 [21,46]. Thus, in our opinion, ESC1 level is related to complex V Si V C .…”

“…The performance of semiconductor devices is dictated ultimately by the presence and behavior of point defects. Defects in SiC and GaAs are under intensive study [20][21][22][23]. At the same time, more detailed information regarding the MWT influence on the deep level parameters is practically unknown.…”

Defect-Induced Luminescence Quenching of 4H-SiC Single Crystal Grown by PVT Method through a Control of Incorporated Impurity Concentration

“…C N (atoms/cm The DAP recombination rate is an efficient measure of emission luminescence [33][34][35]. The RDA is proportional to the donor concentration (C D ) and acceptor concentration (C A ).…”

“…The increase in PL intensity of N-B DAP for S2 was shown to be due to an increase in C N . The Aukerman and Millea model [33][34][35] suggests that the correlation between the DAP recombination and concentration causes an increase in PL intensity with the increase in the difference between C N and C B , which is called the N-B concentration gap. When the N-B concentration gap is larger than C B , it becomes saturated.…”