Defects distribution and evolution in selected-area helium ion implanted 4H-SiC

An experimental demonstration of the generation of V-Si, CSiVC, and NCVSi color centers in 4H-SiC using helium ion microscope irradiation of 5 x 5 mu m(2) areas with subsequent annealing treatment is presented. With the aid of transmission electron microscopy (TEM), photoluminescence (PL) and cathodoluminescence (CL) spectroscopy and Raman stress analysis, the evolution and distribution of color centers were thoroughly investigated. Cross-sectional TEM revealed the presence of helium bubbles in the center of the regions implanted with high doses which account for the observed quench of PL emission in the center of the implanted regions in both PL and CL measurements. PL spectra from the virgin, implanted and annealed samples proved the appearance of V-Si after implantation and the transformation from V-Si to CSiVC and NCVSi centers after annealing at 1000 degrees C. Moreover, with the increase of the implantation dose, the area of NCVSi centers increases whereas that of CSiVC decreases, which provide the first evidence of the competitive relationship between the formation of CSiVC and NCVSi defects. The comparison between stress distribution and CSiVC defect distribution illustrated that CSiVC centers predominantly distributed around the surface rupture region after thermal annealing where significant stress repair occurred. The results show that focused helium ion implantation holds promise for the precise coupling of V-Si, CSiVC and NCVSi centers in predefined locations in integrated photonics applications.