Self-Balancing Position-Sensitive Detector (SBPSD).

Area of Science:

• Optoelectronics
• Semiconductor device physics

Background:

• Optical position-sensitive detectors (PSDs) are non-contact sensors for light spot localization.
• Silicon-based PSDs utilize CMOS technology, offering affordability and real-time analog output.
• Existing commercial PSDs have limited length availability (up to 37 mm).

Purpose of the Study:

• To develop an innovative optical position sensor that eliminates the need for external readout circuitry.
• To create a self-balancing position-sensitive detector (SBPSD) with enhanced scalability and performance.
• To demonstrate the feasibility of fabricating longer PSD devices beyond current commercial limitations.

Main Methods:

• Development of a novel optical position sensor design using two back-to-back connected photodiodes.
• Fabrication of prototype self-balancing position-sensitive detectors (SBPSDs) using standard CMOS technology.
• Characterization of prototype devices for linearity, symmetry, and spatial resolution.

Main Results:

• Prototype SBPSDs successfully eliminated the requirement for external readout circuitry.
• Demonstrated linear and symmetric coordinate characteristics across fabricated devices.
• Achieved a spatial resolution of 200 μm for a 74 mm device, significantly longer than commercial PSDs.
• Successfully fabricated prototype devices with lengths up to 100 mm, proving scalability.

Conclusions:

• The developed self-balancing position-sensitive detectors (SBPSDs) represent a significant advancement in optical sensing technology.
• SBPSDs offer a cost-effective, integrated solution for precise light spot tracking with improved scalability.
• The technology holds potential for various applications requiring non-contact position sensing over extended lengths.