Archives for October 2021

ST to Start Quantum Dot Image Sensor Production

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SeekingAlpha article "Quantum Dots - All The Colours Of The Rainbow" by Edison Investment Research tells about ST QD sensor plans. The article is also published in a pdf form.

"STMicroelectronics ready to commercialise QD photodetector platform technology

In May 2021, ST presented a paper at the Society for Information Display’s annual symposium. This announced that the company was ready to commercialise its QD photodetector platform technology and intended to have 940nm engineering samples ready for release to early adopters during calendar H221 and SWIR (<1,400nm) samples ready during calendar 2022. The paper noted that the technology held great promise for enabling lower cost (100–1,000 times lower), high-performance, high-resolution, large spectral response image sensors, which would potentially drive large SWIR imaging growth. It identified initial opportunities in mobile devices, miniature spectrometers and hyperspectral imaging, machine vision and advanced driver assistance, noting that the variant currently at R&D scale was likely to surpass the required performance specifications including sensor speed for time-of-flight applications in future.

We have previously inferred elsewhere that ST is deploying QDs from Nanoco for this application. If successful, this programme could lead to production scale-up and eventual volume production in calendar 2023 at Nanoco’s proven production facility in Runcorn. Nanoco is also working with a ‘very significant’ Asian chemical company on the development of QDs or infra-red sensing applications. The Asian customer intends to incorporate Nanoco’s nanomaterials in its own materials, which it will sell globally to companies making electronic devices (i.e., companies at a similar level in the supply chain to ST). Volume production for the Asian customer is likely to commence one year to 18 months after any potential volume ramp-up for ST."

Investing.com article is based on an earlier version of Edison report giving more details about ST-Nanoco cooperation history:

"Nanoco and ST have been working together for around three years. Originally this was as part of a supply chain for a major US customer, with Nanoco manufacturing nanomaterials that ST used to improve the sensitivity of its silicon infrared sensors. In June 2019 the US customer advised Nanoco that the joint programme would not be extended beyond December 2019 when the contract covering a range of stress tests and commissioning services at the Runcorn facility concluded. This decision was for reasons wholly unconnected to the performance of Nanoco’s materials and service delivery. The nanomaterials production facility in Runcorn had been successfully commissioned, with Nanoco delivering the final milestones for the US customer during FY20 and earning the contracted milestone payments in full.

With the US customer having withdrawn from the scene and the exclusivity agreement with it having lapsed, ST is able to offer the enhanced, proven, near infrared (NIR) sensors developed for the US customer across its extensive, global customer base. In May 2020 ST signed a framework agreement with Nanoco covering both development work and commercial supply of nanomaterials for use in multiple infrared sensing applications over a five-year period. The agreement covers the supply of small-scale volumes of nanomaterials for NIR sensors. It also covered a development project, which initially extended from April to December 2020, on a new generation of nanomaterials for potential use in other infrared sensing applications, which we infer from a recent paper given by ST (see below) are in the short-wave infrared (SWIR) range. This development activity was not impaired by the coronavirus pandemic. During H1/21 Nanoco successfully delivered all of the technical and commercial milestones on the first phase of this project, which contributed £0.8m of the total £1.0m revenues for the period. In May 2021 Nanoco announced that it was working on the second phase, which is the optimisation of the new materials. This phase is scheduled to complete in Q1/22. If successful, this phase could lead to production scale-up and eventual volume production in calendar 2023.

The agreement also commits ST to taking a specified minimum volume of nanomaterials from Nanoco if the enhanced sensors gain market traction and commercial volumes are required. These materials would be produced at the existing facility dedicated to sensing applications in Runcorn."

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Quantum Dot/Graphene Detectors Reviews

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IOP NanoExpress publishes Kansas University paper "Quantum dots/graphene nanohybrids photodetectors: progress and perspective" by Judy Wu and Maogang Gong.

"Semiconductor quantum dots/graphene heterostructure nanohybrids combine the advantages of the enhanced light–matter interaction and spectral tunability of quantum dots (QDs) and high charge mobility in graphene as a charge transport pathway, providing a unique platform for exploration of photodetectors with high performance. In particular, the QDs/graphene nanohybrids allow resolution to the critical issue of charge transport in QDs-only photodetectors stemming from the low charge mobility associated with both QD surface defect states and inter-QD junctions. Furthermore, the achieved capability in industrial-scale fabrication of graphene and colloidal QDs has motivated efforts in research of QDs/graphene nanohybrids focal plane arrays that are expected to be not only high performance and low cost, but also light-weight, flexible and wearable. This paper aims to highlight recent progress made in the research and development of QDs/graphene nanohybrid photodetectors and discuss the challenges remained towards their commercial applications."


Wiley Advanced Science publishes a paper "Integration of Colloidal Quantum Dots with Photonic Structures for Optoelectronic and Optical Devices" by Mengyu Chen, Lihua Lu, Hui Yu, Cheng Li, and Ni Zhao from Xiamen University, Institute of Xiamen, and Chinese University of Hong Kong.

"In this review, the recent advances in this research area are summarized. In particular, the use of four typical photonic structures, namely, diffraction gratings, resonance cavities, plasmonic structures, and photonic crystals, in modulating the light absorption (e.g., for solar cells and photodetectors) or light emission (e.g., for color converters, lasers, and light emitting diodes) properties of QD-based devices is discussed. A brief overview of QD-based passive devices for on-chip photonic circuit integration is also presented to provide a holistic view on future opportunities for QD/photonic structure-integrated optoelectronic systems."

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One-pixel Camera from HDR Inventor

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Steve Mann publishes Instructables article "One-pixel Camera for Teaching and Research on Comparametric Equations and HDR." It starts from a claim of a multi-frame HDR invention in 1996:

"Back in the 1980s and early 1990s I invented something called HDR (High Dynamic Range) imaging that is now widely used in smartphones and cameras and augmented reality vision systems, etc.. My general philosophy was to regard the camera as an array of light meters. The idea is to turn a camera into a scientific measuring instrument."

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GeSn/Ge/Si Detector to Extend SWIR Sensor Sensitivity to 2.45um

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Photonics: Researchers at the Forschungszentrum Jülich (Jülich Research Center) and the Politecnico di Milano (Polytechnic University of Milan) have developed an IR detector that provides a bias-switchable spectral response in two distinct IR bands. When the bias voltage for the detector is reversed, the device switches from the NIR to the SWIR band. The dual-band photodetector is Si-wafer based and is said to be suitable for integration into cameras and smartphones.

The paper "CMOS-Compatible Bias-Tunable Dual-Band Detector Based on GeSn/Ge/Si Coupled Photodiodes" by Enrico Talamas Simola, Vivien Kiyek, Andrea Ballabio, Viktoria Schlykow, Jacopo Frigerio, Carlo Zucchetti, Andrea De Iacovo, Lorenzo Colace, Yuji Yamamoto, Giovanni Capellini, Detlev Grützmacher, Dan Buca, and Giovanni Isella is published in ACS Photonics.

"Here, we present a two-terminal dual-band detector, which provides a bias-switchable spectral response in two distinct IR bands. The device is obtained from a vertical GeSn/Ge/Si stack, forming a double junction n-i-p-i-n structure, epitaxially grown on a Si wafer. The photoresponse can be switched by inverting the bias polarity between the near and the short-wave IR bands, with specific detectivities of 1.9 × 1010 and 4.0 × 109 cm·(Hz)1/2/W, respectively. The possibility of detecting two spectral bands with the same pixel opens up interesting applications in the field of IR imaging and material recognition, as shown in a solvent detection test. The continuous voltage tuning, combined with the nonlinear photoresponse of the detector, enables a novel approach to spectral analysis, demonstrated by identifying the wavelength of a monochromatic beam."

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