Large Area, Full-Color Image Sensors Made with Organic Semiconductors

1999 ◽  
Vol 558 ◽  
Author(s):  
G. Yu ◽  
G. Srdanov ◽  
J. Wang ◽  
A.J. Heeger
Keyword(s):  
Dark Current ◽  
Dynamic Range ◽  
Color Image ◽  
Sensor Arrays ◽  
Blue Color ◽  
Two Dimensional ◽  
Large Area ◽  
Full Color ◽  
Sensing Applications ◽  
Photodiode Arrays

ABSTRACTLarge area polymer photodiode arrays were designed and fabricated for full-color imaging applications. These sensor arrays are of high photosensitivity, low dark current, large dynamic range and fast response time. The red, green and blue color primaries were achieved by coupling a set of color filters with the polymer sensor pixels with broad response covering entire visible spectrum. Image recovery process from the pixel photocurrent data was developed, which is suitable generally to image arrays with power-law light intensity dependence and with finite pixel dark current. Large sensing length photodiode arrays (2.5”5”) were fabricated with pixel densities from 40 to 100 dot-per-inch. They were used as the sensing elements in page size document scanners. Voltage switchable polymer photodetectors were developed. Their photosensitivity can be switched on and off with external bias. These devices can be used as the sensing elements in x-y addressable two-dimensional sensor matrices. The high on/off switching ratio and high photocurrent/dark-current ratio allow such two-dimensional, passive photosensor matrices be used for image sensing applications.

High Sensitivity Polymer Photosensors for Image Sensing Applications

1998 ◽  
Vol 508 ◽  
Author(s):  
Gang Yu ◽  
Jian Wang ◽  
Jon McElvain ◽  
Alan J. Heeger
Keyword(s):  
Dynamic Range ◽  
Spectral Response ◽  
Polymeric Materials ◽  
High Sensitivity ◽  
Large Area ◽  
Image Sensing ◽  
Sensing Applications ◽  
Large Size ◽  
Photodiode Arrays ◽  
High Photosensitivity

AbstractConjugated polymers and polymer blends were developed for photosensing applications. Large size photosensors fabricated in ITO/polymer/metal configuration show high photosensitivity, 0.1-0.4 A/Watt in visible and near UV, as good as that made with inorganic semiconductors. The processability of the polymeric materials allows these photosensors be made in large size, onto substrates in desire shape, or even in flexible form, hybridized or integrated with optical devices or electronic devices. Large area, full-color, digital image sensing is demonstrated using photodiode arrays made from semiconducting polymers. The photodiode arrays, fabricated by casting the semiconducting polymer from solution at room temperature, have high photosensitivity, low dark current and large dynamic range. Photo-detection with desired spectral response or multi-band selection are also demonstrated.

ITO/a-SiNx:H/a-Si:H Photodiode with Enhanced Photosensitivity and Reduced Leakage Current Using Polycrystalline ITO Deposited at Room Temperature

2000 ◽  
Vol 609 ◽  
Author(s):  
S. Tao ◽  
Q. Ma ◽  
D. Striakhilev ◽  
A. Nathan
Keyword(s):  
Leakage Current ◽  
Dark Current ◽  
Room Temperature ◽  
Dynamic Range ◽  
Transport Model ◽  
Measurement Data ◽  
Mis Structure ◽  
Defect States ◽  
Large Area ◽  
Density Of Defect States

ABSTRACTWe report an ITO/a-SiNx:H/a-Si:H MIS photodiode structure based on room temperature deposition of optically transparent polycrystalline ITO for applications in large area optical and x-ray imaging. The photodiode structure exhibits device characteristics with reduced leakage current and enhanced photosensitivity giving rise to a hundred-fold improvement in dynamic range. This notable improvement in performance is believed to be due to the reduced diffusion of oxygen from the ITO to the a-Si:H layer, and thus reducing the density of defect states inside the a-Si:H layer. The behavior of photo and dark current is consistent with an elaborate transport model for the Schottky barrier. The model agrees reasonably well with measurement data for the dark current and provides a consistent picture in terms of the photo current behavior in the MIS structure, where the insulating layer serves to reduce the oxygen diffusion.

Two-Dimensional Amorphous Silicon Color Sensor Array

2001 ◽  
Vol 664 ◽  
Author(s):  
F. Lemmi ◽  
M. Mulato ◽  
J. Ho ◽  
R. Lau ◽  
J. P. Lu ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Dynamic Range ◽  
Imaging System ◽  
Color Image ◽  
Two Dimensional ◽  
Leakage Currents ◽  
Color Sensor ◽  
Low Leakage ◽  
Color Sensors ◽  
Silicon Based

ABSTRACTThis paper reports on the first full realization and characterization of a two-dimensional array of amorphous silicon (a-Si:H) color sensors, addressed by integrated amorphous silicon-based thin-film transistors (TFTs). The array includes 512 × 512 pixels with 75-µm pitch, or about 340 dpi. Each pixel features a color sensor realized by a p-i-n-i-p stack of doped and undoped a-Si:H layers, and the TFT. The color sensors are made of two back-to-back p-i-n diodes, which selectively sense the illumination according to the polarity of the applied bias voltage. The sensor layers are grown on top of the TFTs to improve the array fill factor. The p-in-i-p sensor stack is mesa-isolated into single sensors to reduce cross-talk.Images are acquired using two bias voltages and yield the red and blue/green components of the original with a good color separation. A color image is reconstructed using the information from the two images acquired. Aside from a color bias, which is expected for a two-color reconstruction, the imaging system works well. In particular, the array shows very low leakage currents, which enable a very large dynamic range and sensitivity. In the response of the array to a light pulse, the bottom thick diode ensures a fast drop in the signal after the flash, while the top thin diode exhibits some residual image lag.

Transient current in a-Si:H-based MIS photosensors

2008 ◽  
Vol 1066 ◽  
Author(s):  
Miguel Fernandes ◽  
Yuriy Vygranenko ◽  
Manuela Vieira ◽  
Gregory Heiler ◽  
Timothy Tredwell ◽  
...  
Keyword(s):  
Dark Current ◽  
Elevated Temperatures ◽  
Sensor Arrays ◽  
Charge Trapping ◽  
Transient Current ◽  
Mis Structure ◽  
Current Component ◽  
Large Area ◽  
Semiconductor Interface ◽  
X Ray

ABSTRACTLarge-area amorphous silicon (a-Si:H) sensor arrays are widely used for medical x-ray imaging, nondestructive testing and security screening. Most of the commercially available detectors are of the indirect conversion type, in which an x-ray phosphor screen is optically coupled to an array of a-Si:H sensors. The a-Si:H PIN photodiode and the MIS photoelectric converter are two alternative sensing elements used in these detectors. The major advantage of the MIS structure over PIN is fact that this device has the same layer sequence as the a Si:H TFT switch and therefore, they can be fabricated simultaneously resulting in an effective reduction in the lithography mask count. The main disadvantage of the MIS structure is the higher noise level due to transient dark current. The transient dark current originates from traps at the semiconductor-insulator interface and i-layer bulk defects. In this work we analyze the transient current transport in segmented-gate/SiN/a Si:H/n+/ITO structures under different biasing conditions and temperatures. Using a home-made setup the dark current decay was measured within an interval of 1 second in the temperature range from 294 to 353K. It is found that the dark current component associated with charge trapping at the insulator-semiconductor interface can be largely eliminated by adjusting the bias voltage during the refresh period. Under optimized biasing conditions and elevated temperatures the bulk current component becomes dominant.

TECHNOLOGY OF LARGE AREA TWO-DIMENSIONAL COLOR IMAGE SENSOR

2000 ◽  
Author(s):  
D. Caputo ◽  
G. de Cesare ◽  
F. Irrera ◽  
A. Morgia ◽  
A. Nascetti ◽  
...  
Keyword(s):  
Color Image ◽  
Image Sensor ◽  
Two Dimensional ◽  
Large Area

Low dark current and high dynamic range a-Si:H MSM photodetector for large area medical imaging

2013 ◽  
Author(s):  
Sina Ghanbarzadeh ◽  
Shiva Abbaszadeh ◽  
Michael Adachi ◽  
Karim S. Karim
Keyword(s):  
Medical Imaging ◽  
Dark Current ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Large Area ◽  
Msm Photodetector ◽  
High Dynamic

Large-Area, Full-Color Image Sensors Made with Semiconducting Polymers

1998 ◽  
Vol 10 (17) ◽  
pp. 1431-1434 ◽  
Author(s):  
Gang Yu ◽  
Jian Wang ◽  
Jon McElvain ◽  
Alan J. Heeger
Keyword(s):  
Color Image ◽  
Image Sensors ◽  
Semiconducting Polymers ◽  
Large Area ◽  
Full Color

Computer simulation study about the dependence of amorphous silicon photonic waveguides efficiency on the material quality

2020 ◽  
Vol 90 (3) ◽  
pp. 30502
Author(s):  
Alessandro Fantoni ◽  
João Costa ◽  
Paulo Lourenço ◽  
Manuela Vieira
Keyword(s):  
Amorphous Silicon ◽  
High Throughput Screening ◽  
Simulation Analysis ◽  
Low Cost ◽  
Deposition Process ◽  
Large Area ◽  
Sidewall Roughness ◽  
Sensing Applications ◽  
Fabrication Defects ◽  
The Impact

Amorphous silicon PECVD photonic integrated devices are promising candidates for low cost sensing applications. This manuscript reports a simulation analysis about the impact on the overall efficiency caused by the lithography imperfections in the deposition process. The tolerance to the fabrication defects of a photonic sensor based on surface plasmonic resonance is analysed. The simulations are performed with FDTD and BPM algorithms. The device is a plasmonic interferometer composed by an a-Si:H waveguide covered by a thin gold layer. The sensing analysis is performed by equally splitting the input light into two arms, allowing the sensor to be calibrated by its reference arm. Two different 1 × 2 power splitter configurations are presented: a directional coupler and a multimode interference splitter. The waveguide sidewall roughness is considered as the major negative effect caused by deposition imperfections. The simulation results show that plasmonic effects can be excited in the interferometric waveguide structure, allowing a sensing device with enough sensitivity to support the functioning of a bio sensor for high throughput screening. In addition, the good tolerance to the waveguide wall roughness, points out the PECVD deposition technique as reliable method for the overall sensor system to be produced in a low-cost system. The large area deposition of photonics structures, allowed by the PECVD method, can be explored to design a multiplexed system for analysis of multiple biomarkers to further increase the tolerance to fabrication defects.

scholarly journals Full-color nanorouter for high-resolution imaging

Nanoscale ◽  
2021 ◽  
Author(s):  
Mingjie Chen ◽  
Long Wen ◽  
Dahui Pan ◽  
David Cumming ◽  
Xianguang Yang ◽  
...  
Keyword(s):  
High Resolution ◽  
Color Image ◽  
Image Sensors ◽  
Structural Color ◽  
High Resolution Imaging ◽  
Scaling Effects ◽  
Full Color ◽  
Resolution Imaging

Pixel scaling effects have been a major issue for the development of high-resolution color image sensors due to the reduced photoelectric signal and the color crosstalk. Various structural color techniques...

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