First principle study of V-implantation in highly-doped silicon materials

Density Functional Theory (DFT) has been used to study structural and electronic properties of new compounds based on V-implanted Si and their potential as infrared photodetectors. Effects derived from the implantation of V on bulk-Si are calculated at different configurations, i.e., substitutional (VSi) and interstitial (Vi) positions as well as the effect of Si vacancies. Despite all implantation processes are energetically penalized, Vi-implanted compound leads to the lowest formation energies. Furthermore, interstitial implantation in the vicinity of a Si vacancy would lead to a highly favored process. The analysis of the electronic structure shows that Vi-implanted compounds own an intermediate band (due to t2g states of vanadium atom), which allows new electronic transitions below 1.0 eV. To deal with the bandgap underestimation of common DFT methods, quasiparticle calculations have been applied via the G0W0 approximation. Applied correction to the bandgap based on GW has considerably improved theoretical results compared to experimental ones. The investigation of the absorption features points out that the absorption response can be extended up to infrared region via sub-gap transitions across the intermediate band. This work highlights the potential of V-implanted silicon based materials with infrared response.