Avalanche photodiode thirty-two-element linear array with minimal dead space.

Area of Science:

• Optoelectronics
• Semiconductor device fabrication

Background:

• Avalanche photodiode (APD) arrays are crucial for sensitive light detection.
• Minimizing dead space between elements is essential for high-resolution imaging and reduced signal loss.

Purpose of the Study:

• To present a novel fabrication method for APD arrays with significantly reduced dead space.
• To demonstrate the effectiveness of integrated lenses in minimizing dead regions.

Main Methods:

• Fabrication of a 32-element linear APD array on 150-microm centers.
• Incorporation of an integrated lens array to reduce the effective dead region.
• Characterization of optical and electrical crosstalk, quantum efficiency, and gain uniformity.

Main Results:

• Reduced dead space from ~50 micrometers to a few microns.
• Achieved external quantum efficiency over 80% (0.4–0.95 microm).
• Measured optical and electrical crosstalk of approximately -40 dB up to 10 MHz.
• Gain uniformity of +/-20% within an element and +/-30% over the array at an average gain of 60.

Conclusions:

• The integrated lens array method effectively minimizes dead space in APD arrays.
• The fabricated arrays exhibit high quantum efficiency and low crosstalk, suitable for demanding applications.
• This fabrication technique offers a pathway to improved APD array performance for various optical sensing needs.