  Realization of superconductivity in Group IV semiconductors could have a
strong impact in the direction quantum technologies will take in the future.
Therefore, it is imperative to understand the nature of the superconducting
phases in materials such as Silicon and Germanium. Here, we report systematic
synthesis and characterization of superconducting phases in hyperdoped
Germanium prepared by Gallium ion implantation beyond its solubility limits.
The resulting structural and physical characteristics have been tailored by
changing the implantation energy and activation annealing temperature.
Surprisingly, in addition to the poly-crystalline phase with weakly-coupled
superconducting Ga clusters we find a nano-crystalline phase with quasi-2D
characteristics consisting of a thin Ga film constrained near top surfaces. The
new phase shows signatures of strong disorder such as anomalous B${\rm c}$
temperature dependence and crossings in magentoresistance isotherms. Apart from
using hyperdoped Ge as a potential test-bed for studying signatures of quantum
phase transitions (e.g. quantum Griffith singularity), our results suggest the
possibility of integration of hyperdoped Ge nano-crystalline phase into
superconducting circuits due to its 2D nature.
