Neutral boron-interstitial clusters in crystalline silicon

The formation of B clusters inside ultrashallow junctions is one of limiting factors in the miniaturization process of electronic devices. The assembling of these clusters corresponds to a reduction of the electrical activity of the doping process. Exploiting hierarchically different simulation techniques, we investigate structural and electronic properties of small B clusters inside a crystalline Si matrix. Density-functional--theory-tight-binding molecular dynamics simulations are carried out as scouts selecting the candidates to be analyzed in depth via ab initio calculations. The latter provide insights into the electronic properties of the B clusters, identifying the fingerprints of interstitialcy and chemical composition in their densities of states.