Observation of Distinct Superconducting Phases in Hyperdoped p-type Germanium

Abstract

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$\mathrm{c}$ 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.

References in corpus (14)

• Superconductivity in diamond
• Evidence of topological superconductivity in planar Josephson junctions
• Coherent quantum phase slip
• High Kinetic Inductance Superconducting Nanowire Resonators for Circuit QED in a Magnetic Field
• Gate Controlled Anomalous Phase Shift in Al/InAs Josephson Junctions
• Thickness-Magnetic Field Phase Diagram at the Superconductor-Insulator Transition in 2D
• Phase signature of topological transition in Josephson Junctions
• Theory of quantum metal to superconductor transitions in highly conducting systems
• Nanowire Superinductance Fluxonium Qubit
• Voltage-Controlled Superconducting Quantum Bus
• Bottom-up superconducting and Josephson junction devices inside a group-IV semiconductor
• Anomalous quantum Griffiths singularity in ultrathin crystalline lead films
• Quantum meets classical phase transition: Low-temperature anomaly in disordered superconductors near $B_{c2}$
• Superconductivity in single-crystalline, aluminum- and gallium-hyperdoped germanium