Jonathan Steckel | STMicroelectronics: How does a 1.6-micron PbS quantum dot pixel bypass the fundamental physical limits of silicon in SWIR imaging?
00:03:28.200 - 00:05:37.200
Other snippets from this talk
Summary of the clip:
How does a 1.6-micron PbS quantum dot pixel bypass the fundamental physical limits of silicon in SWIR imaging?
Integrating colloidal quantum dots directly above a silicon readout integrated circuit (ROIC) achieves a 100% fill factor because the active absorption layer sits on top of the pixel circuitry. This "above-IC" architecture decouples the photodiode from the silicon surface area, allowing designers to allocate more silicon estate to complex pixel designs, such as high-performance global shutter circuits, without sacrificing optical collection area.
While silicon displays a sharp band-edge cutoff and poor quantum efficiency in the near-infrared (NIR) and short-wave infrared (SWIR) regions, PbS quantum films feature a highly tunable first excitonic absorption peak. By controlling particle size, the absorption edge can be extended deep into the SWIR spectrum, enabling high quantum efficiency at critical bands like 940 nm and beyond.
STMicroelectronics has successfully shrunk this colloidal QD global shutter pixel down to a 1.6-micron pitch. This sub-2-micron pitch is exceptionally difficult to achieve with conventional compound semiconductor architectures, positioning colloidal QD technology as a highly disruptive, low-cost pathway for high-resolution SWIR sensing in consumer electronics.
In this short video, you can learn:
* The structural advantage of above-IC integration to achieve a 100% fill factor for global shutter pixels.
* How size-tuning colloidal PbS quantum dots overcomes the physical band-gap limitations of bulk silicon.
* The engineering achievement of scaling global shutter QD pixels down to a 1.6-micron pitch on 300mm wafers.
📋 **Clip Abstract** This clip explains how above-IC quantum dot integration enables a 100% optical fill factor and complex global shutter architectures. It highlights the optical advantages of PbS over silicon in the short-wave infrared spectrum, down to a 1.6-micron pixel pitch.
#PbSQuantumDots, #AboveICIntegration, #SWIRImaging, #GlobalShutterPixel, #CMOSImageSensors, #InfraredSensing
This is a highlight of the presentation:
More Highlights from the same talk.
00:00:49.600 - 00:03:11.400
Can ligand engineering turn fragile colloidal quantum dots into robust 300mm CMOS-compatible "quantum films"?
Can ligand engineering turn fragile colloidal quantum dots into robust 300mm CMOS-compatible "quantum films"?
Colloidal quantum dot (QD) technology offers unique advantages for image sensing due to its solution-processability. By engineering the surface ligands, researchers can tune both particle-to-particle spacing—crucial for optimizing carrier mobility—and the absolute energy levels relative to the vacuum level. This precise energetic alignment ensures efficient charge extraction when integrated with adjacent carrier transport layers in the photodetector stack.
The lead sulfide (PbS) system is highly robust during colloidal synthesis, yielding narrow size distributions and uniform particle geometries. At industrial scale, STMicroelectronics processes these nanomaterials to form ultra-dense, close-packed "quantum films." A proprietary passivation process is introduced during formulation to protect the active layers from degradation while maintaining electronic coupling.
This solution-processed chemistry is compatible with back-end-of-line (BEOL) processing, enabling spin-coating directly onto 300mm CMOS wafers. The underlying copper electrodes define the pixel geometry and shape. The final photodiode stack is completed with specialized electron and hole transport layers, a top electrode, robust encapsulation, and micro-lens arrays to maximize photon collection.
In this short video, you can learn:
* How surface ligand exchange modifies carrier mobility and energetic band alignment with adjacent transport layers.
* The scaling parameters of synthesizing and passivating PbS quantum dots for stable wafer-scale deposition.
* The physical integration stack of spin-coating an active quantum film over copper electrodes on 300mm silicon CMOS lines.
📋 **Clip Abstract** This clip covers how STMicroelectronics utilizes ligand engineering to process colloidal lead sulfide quantum dots into dense, highly stable quantum films. It outlines the manufacturing flow of spin-coating these active layers onto 300mm CMOS wafers, culminating in a fully integrated, encapsulated photodiode stack.
#LigandEngineering, #PbSQuantumDots, #BEOLIntegration, #QuantumFilms, #SWIRImageSensors, #ColloidalOptoelectronics
00:08:01.200 - 00:10:36.600
InGaAs vs. SiGe vs. Quantum Dots: Which technology will win the high-volume consumer SWIR imaging race?
InGaAs vs. SiGe vs. Quantum Dots: Which technology will win the high-volume consumer SWIR imaging race?
Short-wave infrared (SWIR) imaging has traditionally been dominated by Indium Gallium Arsenide (InGaAs) sensors, which offer exceptional quantum efficiency and low dark currents but suffer from high manufacturing costs and restricted pixel pitches. In contrast, Silicon-Germanium (SiGe) approaches are emerging but face challenges regarding quantum efficiency and dark current trade-offs, particularly for consumer-grade applications.
Colloidal quantum dot (QD) technology addresses the core bottlenecks of both incumbents by offering a highly competitive cost-to-performance ratio. Because QD films are solution-processed, they bypass the expensive epitaxial growth and hybridization steps required for InGaAs, while achieving sub-2-micron pixel pitches (down to 1.6μm and 2.2μm) that are currently out of reach for commercial InGaAs.
STMicroelectronics has leveraged its 300mm wafer manufacturing infrastructure to scale this technology for high-volume markets. While legacy players remain restricted to larger pixel pitches (typically 5 to 15 microns), industrializing the QD deposition process on 300mm lines enables highly uniform, high-density arrays that meet the tight cost and scale requirements of consumer devices.
In this short video, you can learn:
* A direct comparative analysis of InGaAs, SiGe, and QD technology across pitch, dark current, and manufacturing cost.
* Why solution-processed quantum films bypass the expensive hybridization bottlenecks of epitaxially grown SWIR sensors.
* The strategic positioning of ST's 1.6-micron and 2.2-micron QD pixel pitch against traditional 5-micron InGaAs alternatives.
📋 **Clip Abstract** This clip presents a technical and commercial comparison of InGaAs, SiGe, and colloidal quantum dot technologies for SWIR imaging. It highlights how STMicroelectronics utilizes 300mm wafer infrastructure to scale sub-2-micron QD pixels at a consumer-friendly cost structure.
#ColloidalQuantumDots, #SWIRImaging, #InGaAs, #Sub2MicronPixel, #CMOSImageSensors, #Optoelectronics