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

We demonstrate the formation of radiative defects, known as color centres, in 100 MeV Ag and 25 keV He irradiated semi-insulating 4H-SiC using low-temperature (~77 K) photoluminescence (PL). In PL, the luminescence resulting from radiative recombination of photo-excited carriers (electrons and holes) is studied. In our work, a 266 nm deep UV excitation source is utilized for performing PL measurements. In the range, 850-1150 nm, the photoluminescent peaks ascribed to silicon vacancies (V Si) and unknown defect-related bands (UD3 and UD4) are observed after both ion irradiations. It has also been observed that till an optimum irradiation fluence there is an enhancement of photoluminescence from the ion irradiation-induced defects but further increase in irradiation fluence results in accumulation of photo-absorbing defects, providing pathways for non-radiative processes. In addition, ion irradiation has been shown to suppress the undesirable luminescence in the range 300-600 nm caused by the intrinsic defects in as-grown 4H-SiC.