The tunneling spectra of the electron-doped cuprate ${\text{Pr}}_{2-x}{\text{Ce}}_x{\text{CuO}}_{4-\delta }$ as a function of doping and temperature are reported. We find that the superconducting gap, $\Delta$, shows a BCS-type temperature dependence even for extremely low carrier concentrations. Moreover, $\Delta$ follows the doping dependence of $T_c$, in strong contrast with tunneling studies of the hole-doped cuprates. From our results we conclude that there is a single superconducting energy scale in the electron-doped cuprates.

• Received 11 March 2009

DOI:https://doi.org/10.1103/PhysRevB.80.012508