Superconductivity of MgB2 Layers Prepared on Silicon Substrate by Implantation of Magnesium Ions into Boron Substrate

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%H-2 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 T-c. The transition temperature T-c becomes higher with increasing annealing temperature: T-c = 18 K (for annealing at T-A = 673 K), T-c = 20 K (for annealing at T-A = 773 K), and T-c = 27 K (for annealing at T-A = 873 K).