Distinguishing the effect of surface passivation from the effect of size on the photonic and electronic behavior of porous silicon

CF₄ plasma-passivation enhanced size dependence of the blueshift in photoemission (PL) and photoabsorption (PA), E_2p-level shift, and band-gap expansion of porous silicon was investigated. It was shown that fluorination further enhances the crystal binding intensity. Bond Order-length-strength (BOLS) correlation enabled to unify the observed blueshift in the PL and PA, the energy shift of the Si-2p core level, as well as the dielectric suppression to the effect of atomic coordination number (CN) imperfection of atoms. The BOLS also enabled to discriminate the contribution from bond relaxation and bond nature alteration to both the crystal binding and electron-phonon coupling.