Superconductivity of MgB₂Layers Prepared on Silicon Substrate by Implantation of Magnesium Ions into Boron Substrate

Abstract

The results of investigation of the MgB2 layers prepared on silicon substrate by implantation of Mg ions into boron substrate are presented. After implantation the annealing processes were carried out at temperatures 673 K, 773 K, and 873 K in a furnace in an atmosphere of flowing Ar-4%H2 gas mixture. The samples were characterized by: four-probe electric conductivity measurements and magnetically modulated microwave absorption. Our results showed that due to silicon substrate the diffusion of implanted Mg ions into boron materials should be limited, and the superconducting phase forms a continuous MgB2 layer and the resistivity for all samples fall down to zero below Tc. The transition temperature Tc becomes higher with increasing annealing temperature: Tc = 18 K (for annealing at TA = 673 K), Tc = 20 K (for annealing at TA = 773 K), and Tc = 27 K (for annealing at TA = 873 K).

Oxygen and hydrogen plasma effects on the MgB2 superconductivity

“…The plasma treatment for 1 h reduces the superconducting volume thus increasing the average distance between the superconducting islands. The increase in the average distance decreases the Josephson coupling and thus the transition temperature in the electrical resistivity measurements [21]. The plasma treatment for 2 h reduces the superconducting volume below the percolation threshold, breaking the percolation path for supercurrent thus destroying the macroscopic superconductivity.…”