Low-energy Se ion implantation in MoS 2 monolayers

In this work, we study ultra-low energy implantation into MoS 2 monolayers to evaluate the potential of the technique in two-dimensional materials technology. We use 80 Se + ions at the energy of 20 eV and with fluences up to 5.0·10 14 cm −2 . Raman spectra of the implanted films show that the implanted ions are predominantly incorporated at the sulfur sites and MoS 2−2 x Se 2 x alloys are formed, indicating high ion retention rates, in agreement with the predictions of molecular dynamics simulations of Se ion irradiation on MoS 2 monolayers. We found that the ion retention rate is improved when implantation is performed at an elevated temperature of the target monolayers. Photoluminescence spectra reveal the presence of defects, which are mostly removed by post-implantation annealing at 200 °C, suggesting that, in addition to the Se atoms in the substitutional positions, weakly bound Se adatoms are the most common defects introduced by implantation at this ion energy.