Ge-based Schottky diodes find applications in high-speed devices. However, Fermi-level pinning is a major issue for the development of Ge-based diodes. This study fabricates a Pt/carbon paste (CP)/Ge Schottky diode using low-cost CP as an interlayer. The Schottky barrier height (ΦB) is 0.65 eV for Pt/CP/n-Ge, which is a higher value than the value of 0.57 eV for conventional Pt/n-Ge. This demonstrates that the CP interlayer has a significant effect. The relevant junction mechanisms are illustrated using feasible energy level band diagrams. This strategy results in greater stability and enables a device to operate for more than 500 h under ambient conditions. This method realizes a highly stable Schottky contact for n-type Ge, which is an essential element of Ge-based high-speed electronics.