Characterization of CMOS compatible waveguide-coupled leaky-mode photodetectors

Near-field scanning optical microscopy has been employed for the first time to analyze integrated photodetectors. Waveguide-coupled leaky-mode polysilicon metal-semiconductor-metal photodiodes fabricated in commercial complementary metal-oxide-semiconductor technology for on-chip optical interconnects exhibit a measured effective absorption coefficient of 0.67 dB/μm allowing a 10-μm-long detector to absorb 83% of the light in the waveguide with an estimated responsivity of 0.35 A/W at 654 nm. The measured effective absorption coefficient is in good agreement with effective index mode overlap calculations.