Boron lattice location in room temperature ion implanted Si crystal

Abstract

The B lattice location in presence of a Si-self-interstitial (I Si) supersaturation, controlled by energetic proton bombardment, has been studied by means of ion channelling and massive Monte Carlo simulations. B-doped layers of Si crystals with a B concentration of 1 × 10 20 B/cm 3 were grown by Molecular Beam Epitaxy. Point defect engineering techniques, with light energetic ion implants, have been applied to generate an I Si uniform injection in the electrically active layer. The displacement of B atoms out of substitutional lattice sites was induced by 650 keV proton irradiations at room temperature (R.T.) and the resultant defect configuration was investigated by ion channelling and Nuclear Reaction Analysis (NRA) techniques. Angular scans were measured both through 〈1 0 0〉 and 〈1 1 0〉 axes along the (1 0 0) plane using the 11B(p,α) 8Be nuclear reaction at 650 keV proton energy. Monte Carlo simulated angular scans were calculated considering a variety of theoretical defect configurations, supported by literature, and compared with experimental data. Our experimental scans can be fitted by a linear combination of small (0.3 Å) and large B displacements (1.25 Å) along the 〈1 0 0〉 direction, compatible with the B-dumbbell oriented along 〈1 0 0〉 as proposed by ab initio calculations.