Developing large format, low noise, small pixel InGaAs arrays
Henry Yuan, Mike Meixell, Jiawen Zhang, Philip Bey, Joe Kimchi, Louis C. Kilmer
Teledyne Judson Technologies
Background
Infrared imaging technology plays a crucial role across a broad range of applications — from defense and surveillance to industrial inspection, scientific research, and space exploration. As imaging systems become more sophisticated, they require higher resolution, lower noise, and improved sensitivity — all while maintaining compact form factors and efficient operation at or near room temperature.
InGaAs detector arrays have long been the workhorse material for near-infrared (NIR) and short-wave infrared (SWIR) imaging, thanks to their excellent spectral response, fast response time, and ability to operate without deep cooling. However, as end users demand larger arrays, smaller pixels, and better noise performance, traditional InGaAs sensor designs are reaching their physical and performance limits.
Challenge
The drive toward smaller pixel sizes (<10 μm) and larger array formats (>2K × 2K) introduces several technical challenges that must be addressed for next-generation imaging systems:
- Dark current noise: As pixel size decreases, dark current — the unwanted electrical current that flows even without incident light — becomes a significant source of noise, degrading detector sensitivity and limiting low-light performance.
- Capacitance-related noise: Shrinking pixel dimensions can also lead to increased detector capacitance, which raises noise levels and reduces signal-to-noise ratio (SNR), particularly in low-light-level (LLL) applications.
- Manufacturing scalability: Fabricating large-format arrays with small, uniform pixels requires advanced wafer processing techniques to ensure consistent quality, yield, and reliability.
- System performance trade-offs: Historically, reducing pixel size has come at the expense of full well capacity, dynamic range, and noise performance — trade-offs that are unacceptable for high-performance imaging systems.
Figure 1: TJT InAs photodiodes, available in room temperature or TE-cooled formats
Solution
Teledyne Judson Technologies (TJT) is addressing these challenges with cutting-edge developments in small-pixel, large-format InGaAs detector arrays designed to deliver exceptional performance at or near room temperature. Key advancements include:
- Sub-10 μm pixel technology: TJT is actively developing detector arrays with pixel pitches below 10 μm and has successfully fabricated test arrays with pixel sizes as small as 5 μm. This breakthrough significantly increases spatial resolution, enabling higher image detail and precision for advanced imaging applications.
- Low dark current performance: Through optimized material growth and device design, TJT has achieved dramatically reduced dark current density in 10–20 μm pixel arrays, maintaining high sensitivity even without deep cooling.
- Capacitance reduction: Innovations in detector architecture and fabrication have effectively minimized capacitance, reducing noise and preserving SNR, even as pixel dimensions shrink.
- Flexible, scalable array production: TJT’s advanced 4-inch InGaAs wafer process supports high-yield manufacturing of large-format arrays. The company now offers four types of 2D InGaAs arrays/FPAs, tailored to different application requirements for spectral response, bias range, capacitance, and dark current.
These advancements are particularly beneficial for low-light-level imaging, where minimizing noise and maximizing sensitivity are paramount, such as in surveillance, hyperspectral imaging, autonomous navigation, and spaceborne remote sensing.
Conclusion
TJT’ work on low-dark-current, small-pixel, large-format InGaAs detector arrays represents a significant leap forward for infrared imaging technology. By overcoming the historical challenges of pixel scaling, dark current, and capacitance, TJT is enabling next-generation detectors that deliver higher resolution, lower noise, and superior sensitivity — all in compact, scalable designs that operate efficiently at or near room temperature.
These innovations are paving the way for the next era of infrared imaging systems, meeting the evolving demands of scientific, industrial, defense, and space applications around the world.
Read the original published article here:
Low dark current small pixel large format InGaAs 2D photodetector array development at Teledyne Judson Technologies
Henry Yuan, Mike Meixell, Jiawen Zhang, Philip Bey, Joe Kimchi, Louis C. Kilmer
Abstract
Teledyne Judson Technologies (TJT) has been developing technology for small pixel, large format, low dark current, and low capacitance NIR/SWIR InGaAs detector arrays, aiming to produce <10μm pixels and >2Kx2K format arrays that can be operated at or near room temperature. Furthermore, TJT is now developing technology for sub-10μm pixel arrays in response to requirements for a variety of low light level (LLL) imaging applications. In this paper, we will review test data that demonstrates lower dark current density for 10-20μm pixel arrays. We will present preliminary results on the successful fabrication of test arrays with pixels as small as 5μm. In addition, a lot of effort has been made to control and reduce the detector pixel capacitance which can become another source of detector noise. TJT is also developing 4" InGaAs wafer process and now offers four different types of InGaAs 2D arrays/FPAs that are tailored to different customer requirements for dark current, capacitance, spectral response, and bias range.
Reference
Henry Yuan, Mike Meixell, Jiawen Zhang, Philip Bey, Joe Kimchi, and Louis C. Kilmer (31 May 2012) Low dark current small pixel large format InGaAs 2D photodetector array development at Teledyne Judson Technologies, Proc. SPIE 8353, Infrared Technology and Applications XXXVIII, 835309; https://doi.org/10.1117/12.921232
