In this thesis, we use high-resolution Raman and photoluminescence spec- troscopy to investigate the e¤ect of quantum con…nement at dry etched sili- con nanotips. We …rmly establish that the phonon con…nement occur at the silicon nanotips. In addition, we observe an enhanced photoluminescence intensity of no-phonon transitions which may be due to the relaxation of momentum selection rule in silicon nanotips. Besides, an enhanced Raman scattering from the silicon nanotips that might be attributed to the strong internal …eld was also investigated. The research for small-sized silicon is quite important in nowadays semiconductor industry. We hope that the obtained information would be useful to enhance the prospects for realizing the integration of Si based optoelectronic devices and would o¤er as guideline for further application.