  A direct patterning technique of gallium-irradiated superconducting silicon
has been established by focused gallium-ion beam without any mask-based
lithography process. The electrical transport measurements for line and square
shaped patterns of gallium-irradiated silicon were carried out under self-field
and magnetic field up to 7 T. Sharp superconducting transitions were observed
in both patterns at temperature of 7 K. The line pattern exhibited a signature
of higher onset temperature above 10 K. A critical dose amount to obtain the
superconducting gallium-irradiated silicon was investigated by the fabrication
of various samples with different doses. This technique can be used as a simple
fabrication method for superconducting device.
