Investigations on the structural and optical properties of the swift heavy ion irradiated 6HSiC

Single crystal 6HSiC wafers have been irradiated with 150 MeV Ag12+ ions with fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2 at 300 K. The defect accumulation as a function of fluence was studied to determine changes in structural and optical properties. The variation in the fundamental Raman modes of the crystalline 6HSiC due to irradiation has been correlated with the disorder accumulation. The creation of defect states due to irradiation in the bandgap affects the blue-green photoluminescence emission in the irradiated samples. The UV–Visible absorption studies support the existence of defect states in the bandgap which is observed by the shift in the absorption edge towards the lower energy side with increasing fluence. Time Correlated Single Photon Counting photoluminescence decay results suggest that the existing defect states are radiative, exhibiting three lifetimes when irradiated with a fluence 5 × 1011 ions/cm2. The total number of lifetime components was reduced for a fluence 1 × 1013 ions/cm2 as the defect states produced increase the non-radiative defect centres. These results suggest that the accumulation of defects due to irradiation at fluences 5 × 1011 and 1 × 1013 ions/cm2 are degenerate configurations which exhibit multiple lifetimes in photoluminescence studies. It is inferred that the optically active defect states influence the transition rate of charge carriers in this device material.

Research highlights
► We have reported the structural and optical properties of SHI irradiated 6H-SiC.
► The change in Raman modes evidences the disorder accumulation with respect to ion fluence.
► The disorder also causes the modification in the optical properties.
► The time resolved photoluminescence reflects multiple lifetimes due to the degenerate defects states.
► The study also reveals the presence of partial amorphous region due to SHI irradiation.