Current density-voltage characteristics of Si p<sup>+</sup> -i-n<sup>+</sup> Esaki tunneling diodes are presented, which are grown with low-temperature molecular beam epitaxy. The Esaki structures are realized without a postgrowth annealing step. A maximum peak-to-valley current ratio of more than 5 was obtained at room temperature. To the authors' knowledge, this result is the highest reported value for any pure Si tunnel diode. A temperature study of the current density-voltage characteristics separates all three forward current density components: 1) interband tunneling current density; 2) excess current density through defect-assisted tunneling; and 3) diffusion current density. The results show the high potential for the future development of Si Esaki tunneling diodes and predict an increase of the peak-to-valley current ratio up to 15 if the excess current density is suppressed.