SWIR imaging using PbS QD photodiode array sensors.

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Short-wavelength infrared (SWIR) imaging is crucial for various applications.
• Traditional III-V semiconductor-based SWIR sensors are often expensive and complex to fabricate.
• There is a need for cost-effective and high-performance SWIR imaging solutions.

Purpose of the Study:

• To fabricate and characterize a high-resolution lead sulfide quantum dot (PbS QD) photodiode array for SWIR imaging.
• To evaluate the performance metrics of the QD photodiode array, including responsivity, uniformity, response time, and bandwidth.
• To demonstrate the potential of QD photodiode arrays as a viable alternative to III-V SWIR image sensors.

Main Methods:

• Fabrication of a 1 × 10 PbS QD photodiode array using a customized photolithographic process with multiple stacked QD layers.
• High-resolution patterning of the QD layers.
• Characterization of the photodiode array's responsivity, uniformity, response time, and bandwidth under 1310-nm SWIR illumination.
• Development of a prototype 1310-nm SWIR imager.

Main Results:

• The QD photodiode array exhibited average responsivities of 5.54 × 10^-3 A/W at 0 V and 1.20 × 10^-2 A/W at -1 V under 1310-nm illumination.
• Pixel responsivity showed a standard deviation under 10%, indicating excellent uniformity.
• The array achieved a response time of 2.2 ± 0.13 ms and a bandwidth of 159.1 Hz.
• A prototype SWIR imager demonstrated successful image acquisition.

Conclusions:

• PbS QD photodiode arrays can be fabricated with high-resolution patterning.
• The developed QD photodiode array demonstrates competitive performance metrics for SWIR imaging.
• QD photodiode-based SWIR image sensors present a cost-effective and practical alternative to III-V SWIR image sensors.