Sn-loss effect in a Sn-implanted a-SiO2 host-matrix after thermal annealing: A combined XPS, PL, and DFT study

摘要

Amorphous a-SiO2 host-matrices were implanted with Sn-ions with and withoutposterior thermal tempering at 900 {\deg}C for 1 hour in ambient air. X-rayphotoelectron spectroscopy analysis (XPS core-levels, XPS valence bandmapping), photoluminescence (PL) probing, and density functional calculations(DFT) were employed to enable a detailed electronic structure characterizationof these samples. It was experimentally established that the process ofSn-embedding into the a-SiO2 host occurs following two dissimilar trends: theSn4+ -> Si4+ substitution in a-SiO2:Sn (without tempering), and Sn-metalclustering as interstitials in a-SiO2:Sn (900 {\deg}C, 1 hour). Both trendswere modeled using calculated formation energies and partial densities ofstates (PDOS) as well as valence band (VB) simulations, which yielded evidencethat substitutional defect generation occurs with the help of ion-implantationstimulated translocation of the host-atoms from their stoichiometric positionsto the interstitial void. Experimental and theoretical data obtained coincidein terms of the reported Sn-loss effect in a-SiO2:Sn (900 {\deg}C, 1 hour) dueto thermally-induced electronic host-structure re-arraignment, which manifestsas backward host-atoms translocation into stoichiometric positions and theposterior formation of Sn-metal clusters.