Dark Current Limiting Mechanisms in CMOS Image Sensors

McGrath, Daniel; Tobin, S. P.; Goiffon, Vincent; Magnan, Pierre; Roch, Alexandre Le

doi:10.2352/issn.2470-1173.2018.11.imse-354

Cited by 15 publications

(15 citation statements)

References 2 publications

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“…At present, to understand the dark current source of an image sensor, the histogram of a dark frame is used to analyze a specific generation mechanism [4][5][6]. The Dark Current Spectroscopy technique helps estimate the defect density, cross-section and activation energy values from the peak values of a dark current histogram for varying device temperature [3,6,7]. Although the Dark Current Spectroscopy provides information about the nature of defects, it is not sufficient to conclusively differentiate between the contribution of interface and bulk region defect generation in a pixel.…”

Section: Introductionmentioning

confidence: 99%

WITHDRAWN: Dark Current in Pinned Photodiode CMOS Image Sensors: A Pre-Fabrication Physics-based Model

Suharwerdi

Qazi

2023

Preprint

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The present technique to find a dark current source in an image sensor, i.e., Dark Current Spectroscopy, is not sufficient to conclusively differentiate between the contribution of interface and bulk defect generation in a pixel. Also, the dark current data is available only post-fabrication. In this work, the Dark current vs Transfer Gate-off voltage curve is used to extract the defect density-cross-section product, activation energy and maximum carrier lifetime for two important device generation sites, i.e., interface under the Transfer Gate and Pinned Photodiode depletion region. A comprehensive analytical dark current model is formulated and validated using TCAD simulation and experimental data reported in the literature. The temperature variation is incorporated using the Arrhenius relation corresponding to the specific activation energy level. The proposed model along with the Arrhenius relation provides a sufficient pre-fabrication dark current estimate.

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Section: Introductionmentioning

confidence: 99%

WITHDRAWN: Dark Current in Pinned Photodiode CMOS Image Sensors: A Pre-Fabrication Physics-based Model

Suharwerdi

Qazi

2023

Preprint

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“…Although many dark current measurements of pinned photodiodes have been presented, to our knowledge, no study explains and demonstrates the possibility of dark current reduction by sharing mechanisms between adjacent PN junctions. Indeed, if a dark current curve versus the off Transfer Gate (TG) voltage (V LOTG ) is analyzed [8], [9], it shows 2 different regimes ( Fig. 1):…”

Section: Introductionmentioning

confidence: 99%

Dark Current Sharing and Cancellation Mechanisms in CMOS Image Sensors Analyzed by TCAD Simulations

Marcelot

Goiffon

Rizzolo

et al. 2017

IEEE Trans. Electron Devices

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TCAD simulations are conducted on a 4T PPD pixel, on a conventional gated photodiode, and finally on a radiation hardened pixel. Simulations consist in demonstrating that it is possible to reduce the dark current due to interface states brought by the adjacent gate, by means of a sharing mechanism between the photodiode and the drain. The sharing mechanism is activated and controlled by polarizing the adjacent gate at a positive off voltage, and consequently the dark current is reduced and not compensated. The drawback of the dark current reduction is a reduction of the full well capacity of the photodiode, which is not a problem when the pixel saturation is limited by the readout chain. Some measurement performed on pixel arrays confirm the TCAD results.

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“…The dark current of PN photodiodes increases as the intrinsic carrier density increases, which is many orders of magnitude lower for silicon carbide, compared to silicon 32 . As a result, the typical dark currents are around 1 pA cm −2 and 1 fA cm −2 for silicon and 4H-SiC respectively 1 , 33 . Since the reported values are constant over area, the measured dark current is dominated by shared geometries such as the substrate and contacts.…”

Section: Resultsmentioning

confidence: 99%

Integrated 64 pixel UV image sensor and readout in a silicon carbide CMOS technology

et al. 2022

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This work demonstrates the first on-chip UV optoelectronic integration in 4H-SiC CMOS, which includes an image sensor with 64 active pixels and a total of 1263 transistors on a 100 mm2 chip. The reported image sensor offers serial digital, analog, and 2-bit ADC outputs and operates at 0.39 Hz with a maximum power consumption of 60 μW, which are significant improvements over previous reports. UV optoelectronics have applications in flame detection, satellites, astronomy, UV photography, and healthcare. The complexity of this optoelectronic system paves the way for new applications such harsh environment microcontrollers.

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Dark Current Limiting Mechanisms in CMOS Image Sensors

Cited by 15 publications

References 2 publications

WITHDRAWN: Dark Current in Pinned Photodiode CMOS Image Sensors: A Pre-Fabrication Physics-based Model

WITHDRAWN: Dark Current in Pinned Photodiode CMOS Image Sensors: A Pre-Fabrication Physics-based Model

Dark Current Sharing and Cancellation Mechanisms in CMOS Image Sensors Analyzed by TCAD Simulations

Integrated 64 pixel UV image sensor and readout in a silicon carbide CMOS technology

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