Si surface orientation dependence of SiC-dot formation in bulk-Si using hot-C+-ion implantation technique

We experimentally investigated the Si surface orientation dependence of SiC-dot formation and photoluminescence (PL) properties in three (100)-, (110)-, and (111)-bulk-Si substrates (C+–Si) with different surface densities of Si atoms (NS), where SiC-dots were fabricated by a hot-C+ ion implantation into bulk-Si and post-N2 annealing processes. Transmission electron microscopy observation and x-ray photoelectron spectroscopy revealed the formation of SiC-dots in the (110)- and (111)-C+–Si, in addition to (100)-C+–Si. The diameter (Φ) and surface density (ND) of the SiC-dots depended on the Si surface orientation, and the average Φ of the SiC-dots in three surface-oriented C+–Si decreased from approximately 5–3 nm with increasing NS because the trapping value of C-ions at SiO2/Si interface increased with increasing NS, which leads to the reduction of C-ions to convert SiC-dots in the SiC-dot formation area under higher NS condition. However, the UV-Raman intensity of the TO mode of Si−C vibration was nearly independent of NS. We experimentally confirmed the PL emissions from the (110)- and (111)-C+–Si in addition to the (100)-C+–Si. As a result, the PL spectrum and PL emission coefficient (η) of the SiC-dots strongly depended on the Si surface orientation. The PL intensity IPL of the SiC-dots strongly depended on the NS because the η of the SiC-dots significantly increased with decreasing Φ, although SiC-dots in Si substrate are not quantum dots. Consequently, IPL of SiC-dots can be improved in a Si substrate with higher NS.