Ge-on-Si Photodetector With Broadband Spectral Response and High Gain

We propose a photodetector, referred to as the germanium photodiode–body-biased MOSFET (GePD-MOS), which integrates a Ge-on-Si photodiode with a body-biased MOSFET to achieve high gain and broadband short-wavelength infrared (SWIR) detection. In this architecture, the photo-induced body effect acts in conjunction with gate control to modulate the channel current, enabling gain-tunable and high-responsivity operation. Technology Computer-Aided Design (TCAD) simulations were conducted with calibrated material parameters accounting for threading dislocation effects, and the device structure was optimized to enhance optoelectronic performance. The results demonstrate high responsivity and wide spectral coverage extending from the UV to the SWIR region. A proof-of-concept prototype, experimentally implemented by wire-bonding a commercial Ge photodiode to a MOSFET substrate, confirms the photo-induced body effect in agreement with the simulated trend. A peak responsivity of 104 A/W at 1550 nm and 3 A/W at 245 nm was observed. These findings indicate that the GePD-MOS design offers an effective solution for broadband, high-sensitivity detection, with potential CMOS compatibility and applications in imaging, multispectral sensing, and integrated photonics.