Hybrid MOS-PN photodiode with positive feedback for pulse-modulation imaging

Area of Science:

• Photonics and Semiconductor Devices
• Integrated Circuit Design
• Optoelectronics

Background:

• Traditional photodetectors often require complex analog processing for time-based measurements.
• Existing solutions can be bulky and power-intensive, limiting integration possibilities.

Purpose of the Study:

• To propose and characterize a new CMOS-compatible photodetector with intrinsic light-to-time conversion.
• To enable direct time-to-digital conversion at the photodetector output, bypassing analog stages.
• To demonstrate a device suitable for miniaturized and efficient optical sensing systems.

Main Methods:

• Device fabrication using a standard 0.18µm CMOS process.
• Utilizing a deeply depleted MOS structure controlling a forward-biased PN diode.
• Employing Technology Computer-Aided Design (TCAD) simulations for parameter analysis.
• Experimental characterization under varying bias and illumination conditions.

Main Results:

• Demonstrated intrinsic light-to-time conversion capability.
• Achieved direct start of time-to-digital conversion, eliminating analog front-end.
• TCAD simulations validated the impact of semiconductor parameters and bias.
• Experimental measurements confirmed excellent linearity, internal gain, and noise performance.

Conclusions:

• The proposed photodetector offers a simplified and efficient approach to optical time measurements.
• Its CMOS compatibility and promising performance metrics pave the way for integrated optoelectronic systems.
• This device represents a significant advancement in photodetector technology for digital signal processing.