  Weakly disordered two-dimensional (2D) superconductors can host richer
quantum phase transitions than their highly-disordered counterparts. This is
due to the insertion of a metallic state in the transition between a
superconductor and an insulator. Disorders were predicted to show profound
influences on the boundaries surrounding this intermediate metallic phase,
affecting the existence of a metallic ground state called Bose metal and the
dynamic processes in a quantum Griffiths state. Here we present a study on
quantum phase transitions of a clean 2D superconductor, MoS2, under a
perpendicular magnetic field as a function of disorder strength that is tuned
electrostatically. We found two universal scaling behaviors independent of
disorders: a power-law scaling applies for all metallic states, and an
activated dynamical scaling characterizes transitions between quantum Griffiths
state and weakly localized metal. A study over a range of disorder states in
this unexplored clear regime suggests that a Bose metal ground state is
expected only after reaching a critical cleanness. Whereas, stronger disorder
stabilizes a true 2D superconductivity and enhances the quantum Griffiths
phase.
