Some investigations of the superconductor-insulator (SI) transitions in two dimensions have been hindered by aspects of the intrinsic disorder of the studied systems. As a solution to this problem, we have induced superconductivity in insulating, ultrathin films of amorphous bismuth by utilization of the electric field effect. This method of tuning the SI transition does not alter the intrinsic disorder. Analysis of the response to transferred charge density has revealed that screening and the density of states are both involved. This SI transition has been analyzed as a quantum phase transition using a finite size scaling analysis with electron concentration as a tuning parameter, yielding a critical exponent product vz = 0.7 ± 0.05. If z = 1 as expected, this product is consistent with the universality classes of the (2D+1) XY model and the 2D Boson Hubbard model in the absence of disorder.