We report the recent progress of waveguide-coupled O-band GeSi quantum confined stark effect electroabsorption modulators, monolithically integrated in a Si photonics platform on 300 mm Silicon-on-insulator wafers with 220 nm thick Si top layer. A wafer-scale analysis of static insertion loss (IL) and extinction ratio (ER) is presented, showing IL down to 7.5 dB with ER of 5 dB for a 36.8 µm long device, at drive voltages of 2 V peak-to-peak. Modulation bandwidths beyond 50 GHz are demonstrated, with an extracted junction capacitance of 57 fF and series resistance of 8.3 Ω. Finally, open eye diagrams are demonstrated for non-return-to-zero on-off keying (NRZ-OOK) modulation for data rates from 40 Gb/s up to 64 Gb/s, with dynamic extinction ratio of 2.5 dB, at 1320 nm wavelength.