Chemical disorder of a-SiC layer induced in 6H-SiC by Cs and I ions co-implantation: Raman spectroscopy analysis

Single crystals of 6H-SiC wafers were sequentially co-implanted with 360 keV Cs and I ions to a fluence of 1 x 10(16) cm(-2) at room temperature. The Monte Carlo simulation code, Stopping and Range of Ions in Matter (SRIM) was used to simulate the implanted ions in SiC. The SRIM simulation showed that in the co-implanted 6H-SiC, the initial implantation of Cs ions at a dose of 36 displacements per atom (dpa) highly amorphized the SiC structure producing a shallow amorphous SiC (a-SiC) layer of about 200 nm, and the subsequent implantation of I ions at a dose of 35 dpa caused more amorphization, especially to partially distorted/disordered parts of the a-SiC layer. This was confirmed by Raman spectroscopy and imaging analysis which also revealed that ion implantation induced the appearance of several new Si-Si and C-C homonuclear and Si-C heteronuclear bonds in the a-SiC network. The homonuclear bonds play a vital role in amorphization which proceeds through the accumulation of Frenkel pairs and antisite defects. The line-shapes of the Raman signals recorded for a-SiC layer resembles that of amorphous SiC, in the spectral region characteristic of homonuclear bonds in particular.