Vertical incidence photodiodes were fabricated from Ge grown epitaxially on Si(100) by low-energy plasma-enhanced chemical vapor deposition. Consideration of the energy band profiles of n - i - p and p - i - n heterostructures, and optimization of growth processes and thermal budget, allowed the performance of Ge photodectors integrated on Si(100) substrates to be optimized. Record low dark current density of J s = 4.1 × 10 − 5 A / cm 2 and external quantum efficiency at 1550 nm of η = 32 % were measured.