Advanced features of layered-structure organic-photoconductive-film CMOS image sensor: Over 120 dB wide dynamic range function and photoelectric-conversion-controlled global shutter function

Nishimura, Kazuko; Shishido, Sanshiro; Miyake, Yuichi; Kanehara, Hidenari; Hirase, J.; Sato, Yoshiaki; Tomekawa, Yuko; Yamasaki, Masayuki; Murakami, Masashi; Harada, Masahiko; Inoue, Yasunori

doi:10.7567/jjap.57.1002b4

Cited by 23 publications

(19 citation statements)

References 27 publications

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“…Organic photodetectors (OPDs) have attracted substantial research interest for photodetection and imaging technologies because of their advantages of high responsivity, sensitive dynamic range, and ease of large area fabrication; [1,2] such devices have all the necessary ingredients to be used in high-end applications. [3][4][5] For image sensors, monolithic integration of an effects, [18][19][20][21][22] indicating that these OPDs can exhibit a specifically spectral response, which is promising to achieve a self-filtering sensor without additionally optical filters. On the other hand, inverted devices also demonstrate superior stability compared with conventional device structures in both OPD and organic photovoltaic (OPV) technologies, [23,24] where the positions of the cathode and anode are reversed and the unstable interlayers are also replaced by more stable materials.…”

Section: Introductionmentioning

confidence: 99%

Top‐Illuminated Organic Photodetectors beyond 1000 nm Wavelength Response Enabled by a Well‐Defined Interfacial Engineering

Wu¹,

Lai²,

Hsiao³

et al. 2021

Advanced Optical Materials

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OPD and readout integrated circuit (ROIC) enables several advantages. [6] For example, the sensor area can potentially reach a larger fill factor as the OPD is directly overlaid on top of an ROIC, which means that more incident photons will be absorbed by the photoactive layer (PAL), leading to imagers that are more sensitive to light. [5] In addition, the response spectra for organic semiconductors can be designed and tuned by adjusting the chemical structure, and the application of organic-based image sensors can be easily extended by changing the PAL materials with various light responses. [7,8] Among image sensors, near infrared (NIR) and shortwave infrared (SWIR) imaging technologies are essential to many applications, including health monitoring, [9,10] machine vision, [11] optical communication, [12] and spectro scopy. [13] Currently, the semiconductors utilized for the detection of NIR radiation are still determined by silicon (Si) technology, [14] such that the sensor structure requires high-temperature growth and complex bonding processes, and at a cost that remains prohibitive for large-area manufacturing. The external quantum efficiencies (EQEs) of Si-based detectors are also intrinsically limited when the incident light extends to the SWIR region, in which the wavelength (λ) is longer than 1000 nm.Considering various breakthroughs during the development of OPDs, it is noted that improvements that result in high performance always rely on both material innovation and stateof-the-art device engineering. An OPD with high EQEs of 66% and 67% at a wavelength of 940 and 1000 nm has been realized recently by using a specifically designed nonfullerene acceptor (NFA). [15] This result indicates the significant future potential of organic image sensor technology. For device engineering, photo multiplication type OPD has been developed successfully for highly sensitive sensors under weak light condition. Photomultiplication effect is commonly obtained by introducing charge traps in photoactive layer of OPD to realize interfacial trap-assisted charge injection, leading to the EQE larger than 100%, and the additional amplification systems are no longer needed due to its high EQE. [16,17] Also, OPD with narrowband spectral response has also been demonstrated by introducing the photomultiplication and charge injection narrowing Near infrared (NIR) and shortwave infrared (SWIR) image technologies are of interest for many emerging applications. Among photodetector technologies, organic photodetectors (OPDs) are groundbreaking light sensors with unique photon-to-electron responses at various wavelengths that offer limitless flexibility in field applications due to the tunable design of organic semiconductors. Herein, a top-illuminated OPD deposited on bottom aluminum electrode with a spectral response beyond a wavelength of 1000 nm is reported, which suggests a feasibility for image sensors integrated with bottom readout circuit. The results reveal that a device composed of aluminum-doped zinc oxide, nickel oxide, and...

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Section: Introductionmentioning

confidence: 99%

Top‐Illuminated Organic Photodetectors beyond 1000 nm Wavelength Response Enabled by a Well‐Defined Interfacial Engineering

Wu¹,

Lai²,

Hsiao³

et al. 2021

Advanced Optical Materials

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“…With the upsurge in optical sensors for high-resolution imaging devices in the market, new device design concepts are necessary to improve the resolution of conventional complimentary metal oxide semiconductor (CMOS) color imaging sensors (CISs). [1][2][3] A promising solution for improving resolution is to decrease…”

Section: Introductionmentioning

confidence: 99%

High Speed Response Organic Photodetectors with Cascade Buffer Layers

Suganuma

Heo

Minami

et al. 2021

Adv Elect Materials

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the pixel size while maintaining a large effective light detection area per pixel by using a three-dimensional stacking structure. [4,5] For conventional silicon-based CISs, color filters are indispensable for the selective detection of the three primary light colors of red (R), green (G), and blue (B), because the broad absorption band of silicon exists in the wide wavelength range of 400-700 nm. Typically, CISs consist of a two-dimensional color filter array structure composed of R, G, and B pixels, i.e., a Bayer filter pattern. [6] Therefore, it is practically difficult to apply the above mentioned three dimensional stacking structure to conventional silicon based CISs.Against this background, CISs using organic materials can be a promising solution to overcome the limitations of silicon-based CISs. This is because organic materials have a narrow absorption wavelength range intrinsic to each molecule; therefore, color filters are ultimately unnecessary for selective detection of R, G, and B, making a three-dimensional stacked structure practical. Many organic dyes for high-resolution imaging devices have been developed, and it is also possible to design new organic molecules for any purpose, which is an advantage of using organic materials. [7][8][9][10] In this article, we discuss charge transfer rate enhancement in organic photodiodes (OPDs) by the minimization of energy barrier for hole transfer with cascade type hole transport layers (HTLs). Organic G sensors for hybrid CISs consisting of OPDs stacked on a silicon-based two-dimensional R and B sensors arrays, as a suboptimal concept. [11] In this organic on silicon CIS, the effective light detection area per pixel is doubled by stacking G-light sensitive OPDs on a silicon-based CMOS circuit containing R and B color filters. [12][13][14] The OPD performances have been developed to improve quantum efficiency (EQE), dark current, and thermal stability as main parameters. [15][16][17][18][19][20][21][22][23][24] High EQE contributes to higher sensitivity and higher signal to noise ratio (SNR), and less dark current stabilizes the OPD signal and yields higher SNR. Because the organic materials in OPDs are exposed to high-temperature processes, such as passivation, top layer planarization, and micro-lens forming, they should be thermally stable without degrading performance. High-speed responsivity of OPDs is also a desired specification for high-performance CISs. Recently,

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“…In contrast to conventional CMOS image sensors, hybrid image sensors comprising non-Si photoconversion layers and CMOS field-effect transistors (CMOSFETs) have been reported to surpass the performance of Si photodiodes. By utilizing various characteristics of non-Si photoconversion films, hybrid image sensors have demonstrated many interesting performance features, including a high dynamic range 23 , a global-shutter mode 24 , and a high near-infrared (NIR) 25 – 30 and X-ray sensitivity 31 – 34 . By taking advantage of the recent rapid progress in CMOS-stacking technologies, we previously fabricated c-Se-based hybrid CMOS image sensors to demonstrate high-spatial-resolution characteristics 35 .…”

Section: Introductionmentioning

confidence: 99%

Enhanced image sensing with avalanche multiplication in hybrid structure of crystalline selenium photoconversion layer and CMOSFETs

Imura

Mineo

Honda

et al. 2020

Sci Rep

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The recent improvements of complementary metal–oxide–semiconductor (CMOS) image sensors are playing an essential role in emerging high-definition video cameras, which provide viewers with a stronger sensation of reality. However, the devices suffer from decreasing sensitivity due to the shrinkage of pixels. We herein address this problem by introducing a hybrid structure comprising crystalline-selenium (c-Se)-based photoconversion layers and 8 K resolution (7472 × 4320 pixels) CMOS field-effect transistors (FETs) to amplify signals using the avalanche multiplication of photogenerated carriers. Using low-defect-level NiO as an electric field buffer and an electron blocking layer, we confirmed signal amplification by a factor of approximately 1.4 while the dark current remained low at 2.6 nA/cm2 at a reverse bias voltage of 22.6 V. Furthermore, we successfully obtained a brighter image based on the amplified signals without any notable noise degradation.

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Advanced features of layered-structure organic-photoconductive-film CMOS image sensor: Over 120 dB wide dynamic range function and photoelectric-conversion-controlled global shutter function

Cited by 23 publications

References 27 publications

Top‐Illuminated Organic Photodetectors beyond 1000 nm Wavelength Response Enabled by a Well‐Defined Interfacial Engineering

Top‐Illuminated Organic Photodetectors beyond 1000 nm Wavelength Response Enabled by a Well‐Defined Interfacial Engineering

High Speed Response Organic Photodetectors with Cascade Buffer Layers

Enhanced image sensing with avalanche multiplication in hybrid structure of crystalline selenium photoconversion layer and CMOSFETs

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