High-performance thermally-robust C-band GeSi FK electro-absorption modulators on 300-mm silicon photonics platform

We demonstrate a high-performance, thermally-robust, C-band GeSi Franz-Keldysh electro-absorption modulator (FK-EAM) featuring a compact 0.5 x 50 μm² active region on a 300-mm silicon photonics platform. The static electrical and optical performance is experimentally evaluated over wide operating ranges, with wafer-scale results yielding an extinction ratio (ER) of 6.44 ± 0.38 dB and a transmitter penalty (TP) of 9.25 ± 0.15 dB, while the best dies achieve an insertion loss (IL) of ∼ 5 dB, figure-of-merit (FOM = ER/IL) of 1.23, and TP of 8.8 dB at λ = 1550 nm under a 2 V peak-to-peak drive, representing the best reported EAM performance. The temperature-dependent measurements from 25-85 ^∘C show a monotonic red-shift rate of 0.8 nm/^∘C, while maintaining stable performance with ER > 6 dB, FOM > 1, and TP ∼ 9-10 dB across the wafer, demonstrating temperature-robust modulation performance comparable to state-of-the-art room-temperature EAMs. Furthermore, robust EAM operation beyond the nominal design window (∼1590 nm) is sustained even at 85 ^∘C. These results establish GeSi EAMs as a key enabling technology for high-speed, low-power, dense silicon-photonic transceivers, operating reliably in thermally exposed dynamic environments, paving the way for next-generation optical I/O applications.