Controlled generation of photoemissive defects in 4H-SiC using swift heavy ion irradiation

Abstract

Defects in SiC have shown tremendous capabilities for quantum technology-based applications, making it necessary to achieve on-demand, high-concentration, and uniform-density defect ensembles. Here, we utilize 100 MeV Ag swift heavy ion irradiation on n-type and semi-insulating 4H-SiC for the controlled generation of the defects that have attracted a lot of attention. Photoluminescence spectroscopy shows strong evidence of VSi emitters in semi-insulating 4H-SiC. Additionally, irradiation generates photo-absorbing centers that enhance the optical absorption, suppressing the luminescence intensity at higher fluences (ions/cm2). In n-type 4H-SiC, irradiation drastically increases the inter-conduction band transitions, attributed to absorption from trap centers. A clear correlation is found between (i) loss in the intensity of E2 (TO) Raman signal and the enhancement in absorbance at 532 nm and (ii) decoupling of the longitudinal optical phonon–plasmon coupled Raman mode and the reduction in carrier concentration. The optical bandgap decreases with irradiation fluence for semi-insulating 4H-SiC. This is attributed to the formation of disorder and strain-induced localized electronic states near the band edges.

100 Mev Ag and 25 Kev He Induced Defects in 4H-SiC

“…Furthermore, PL measurements in the 850-1150 nm range were carried out to detect luminescence from the near-infrared defects generated after ion irradiation. The irradiated samples (Figures 3(a)) showed VSi related luminescence [18], as well as previously detected defect centres of unknown origin (UD4 and UD3) [17,19]. In figure 3(b), as the Ag irradiation fluence is raised, the PL intensity increases, indicating an increase in the number of defect states.…”

“…According to the previous reports (Ref. [17] and references therein), the reduction in the intensity of luminescence from 4H-SiC after irradiation is attributed to two factors: (i) irradiation-accelerated defect diffusion and (ii) radiation-induced gettering of structural flaws caused by defects that contribute to non-radiative transitions. Furthermore, PL measurements in the 850-1150 nm range were carried out to detect luminescence from the near-infrared defects generated after ion irradiation.…”

Monitoring of the recovery of ion-damaged 4H-SiC with in situ synchrotron X-ray diffraction as a tool for strain-engineering

“…Besides, the role of swift heavy ion irradiation in the generation of controlled defects has also been studied [11]. Further, we have also investigated thermal and ion beam-induced ultrafast thermal spike-assisted annealing of pre-damaged 4H-SiC with initial damage as 0.3 dpa (dpa; displacement per atom, 1 dpa = all atoms are displaced at least once from their respective lattice sites) [12,13]. This damage level marks the saturation of the first step of damage build-up where the lattice has isolated point defects and a smaller number of in-cascade clusters (ref.…”

“…This damage level marks the saturation of the first step of damage build-up where the lattice has isolated point defects and a smaller number of in-cascade clusters (ref. [12] and references therein). The present work has a two-fold objective: (i) to advance understanding of ion irradiation effects and (ii) utilize those for strain-engineering in 4H-SiC.…”

Structural and optical properties of lithium borate glasses under extreme conditions of ion irradiation

“…The optical bandgap is found to decrease as ion irradiation fluence increases. This variation in optical bandgap depends on the defect creation of SHI beam bombardment on the prepared glasses[60,61]. The direct band gap (E g ) is found to decrease from 2.73 to 2.55 ( 0.02 eV) for pristine and irradiated LBO glasses.…”