2D Image Sensing Arrays with NIP Diodes

1993 ◽  
Vol 297 ◽  
Author(s):  
C Van Berkel ◽  
N C Bird ◽  
C J Curling ◽  
I D French
Keyword(s):  
Sensor Arrays ◽  
Image Sensor ◽  
Transient Current ◽  
Medical Applications ◽  
Device Performance ◽  
Large Area ◽  
Active Matrix ◽  
Test Array ◽  
Image Sensing ◽  
Trap Filling

2D image sensor arrays made with a-Si devices on glass over large area are of considerable interest as document scanners and in medical applications. We have made a test array containing a-Si NIP diodes for both the sensors and the active matrix switching devices. The issues of vertical crosstalk and image lag are discussed in relation to the device performance of the switching diode. The vertical crosstalk is controlled by the diode capacitance and the image lag by the high transient current in the device. We speculate that the transient current is a trap filling current in the deep states of the switching diode.

High Resolution, High Fill Factor A-SI:H Sensor Arrays for Optical Imaging

1999 ◽  
Vol 557 ◽  
Author(s):  
J.T. Rahn ◽  
F. Lemmi ◽  
P. Mei ◽  
J.P. Lu ◽  
J.B. Boyce ◽  
...  
Keyword(s):  
Fill Factor ◽  
Sensor Arrays ◽  
Dimensional Structure ◽  
Pixel Size ◽  
Large Area ◽  
Leakage Currents ◽  
Active Matrix ◽  
3 Dimensional ◽  
Layer Contact ◽  
High Fill Factor

AbstractAmorphous silicon large area sensor arrays are in production for x-ray medical imaging. The most common pixel design works very well for many applications but is limited in spatial resolution because the available sensor area (the fill factor) vanishes in small pixels. One solution is a 3-dimensional structure in which the sensor is placed above the active matrix addressing. However, such high fill factor designs have previously introduce cross talk between pixels.We present data for a design in which the a-Si:H p-i-n photodiode sensor layer has a continuous i-layer and top p+-layer, and a patterned n+-layer contact to the pixel. Arrays of 64 μm and 75μm pitch have been fabricated and are the highest resolution a-Si:H arrays reported to date. The resolution matches the pixel size, and sensitivity has been improved by the high fill factor. Comparison is made between arrays with standard TFTs and TFTs with self-aligned source and drain contacts. Data line capacitance is improved by use of the self-aligned contacts.Measurements are included on the contact to bias capacitance. The high fill factor design greatly suppresses lateral leakage currents, while retaining ease of processing. Provided illumination levels remain below saturation, the resolution matches expectation for the pixel size.

Micro-electro-mechanical system fabrication technology applied to large area x-ray image sensor arrays

2001 ◽  
Vol 19 (4) ◽  
pp. 1219-1223 ◽  
Author(s):  
J. H. Daniel ◽  
B. Krusor ◽  
R. B. Apte ◽  
M. Mulato ◽  
K. Van Schuylenbergh ◽  
...  
Keyword(s):  
Mechanical System ◽  
Sensor Arrays ◽  
Micro Electro Mechanical System ◽  
Image Sensor ◽  
Fabrication Technology ◽  
Large Area ◽  
X Ray ◽  
Area X

Hybrid Si Nanowire/Amorphous Silicon FETs for Large-Area Image Sensor Arrays

Nano Letters ◽  
2011 ◽  
Vol 11 (6) ◽  
pp. 2214-2218 ◽  
Author(s):  
William S. Wong ◽  
Sourobh Raychaudhuri ◽  
René Lujan ◽  
Sanjiv Sambandan ◽  
Robert A. Street
Keyword(s):  
Amorphous Silicon ◽  
Sensor Arrays ◽  
Image Sensor ◽  
Large Area ◽  
Si Nanowire

Noise Analysis of Image Sensor Arrays for Large-Area Biomedical Imaging

2008 ◽  
Vol 1066 ◽  
Author(s):  
Jackson Lai ◽  
Denis Striakhilev ◽  
Yuri Vygranenko ◽  
Gregory Heiler ◽  
Arokia Nathan ◽  
...  
Keyword(s):  
Noise Analysis ◽  
Thin Film Transistor ◽  
Sensor Arrays ◽  
Image Sensor ◽  
Large Area ◽  
Silicon Thin Film ◽  
Image Capture ◽  
Design And Optimization ◽  
System Noise ◽  
Major Development

ABSTRACTLarge area digital imaging made possible by amorphous silicon thin-film transistor (a-Si TFT) technology, coupled with a-Si photo-sensors, provides an excellent readout platform to form an integrated medical image capture system. Major development challenges evolve around optimization of pixel architecture for detector fill factor, and manufacturability, while suppressing noise stemming from pixel array and external electronics. This work discusses the behavior and modeling of system noise that arises from imaging array operations. An active pixel sensor (APS) design with on-pixel amplification is studied. Our evaluation demonstrates that a 17 inch by 17 inch array can achieve system noise as low as 1000 electrons through proper design and optimization.

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.

Image Sensor Arrays with Organic Photoconductors

2001 ◽  
Vol 665 ◽  
Author(s):  
R. A. Street ◽  
J. Graham ◽  
Z. Popovic ◽  
A. Hor ◽  
M. Mulato ◽  
...  
Keyword(s):  
Sensor Arrays ◽  
Image Sensor ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Transport Layer ◽  
Silicon Thin Film ◽  
Active Matrix ◽  
Sensor Material ◽  
Low Leakage ◽  
Low Leakage Current

ABSTRACTTwo-dimensional image sensor arrays incorporating an organic light sensor are reported, with potential application to digital cameras and x-ray imaging. The 512×512 element array has pixel size of 100 micron, and operates with active matrix addressing using amorphous silicon thin film transistors. The array design allows the use of a continuous layer of the organic sensor material without the need for pixel-level patterning. The sensor is a bilayer comprising a thin generator layer and a thicker hole transport layer. Generator materials benzimidazole perylene (BZP) and hydroxy gallium phthalocyanine (HOGaPc) have been studied, with a tetraphenyldiamine (TPD) transport layer. Both sensors give excellent imaging properties with low leakage current, good charge collection and high spatial resolution.

High Fill Factor a-Si:H Sensor Arrays with Reduced Pixel Crosstalk

2008 ◽  
Vol 1066 ◽  
Author(s):  
Yuriy Vygranenko ◽  
A. Sazonov ◽  
D. Striakhilev ◽  
J. H. Chang ◽  
G. Heiler ◽  
...  
Keyword(s):  
Fill Factor ◽  
Sensor Arrays ◽  
Image Sensor ◽  
Low Noise ◽  
Active Matrix ◽  
Interlayer Dielectric ◽  
Sensor Performance ◽  
Data Line ◽  
High Fill Factor ◽  
Low K

ABSTRACTIn this paper, we report on low noise, high fill factor amorphous silicon (a-Si:H) image sensor structures for indirect radiography. Two types of the sensor arrays comprising n-i-p photodiodes and m-i-s photosensors have been fabricated. The device prototypes contain 100 × 100 pixels, with a pixel pitch of 139 μm. The active-matrix addressing is provided by low off-current TFTs. The sensors are vertically integrated onto the TFT-backplane, by implementing a 3-μm-thick low-k interlayer dielectric. This dielectric layer serves to reduce the data line capacitance and to planarize underlying topography. The detector was designed for reduced data-line resistance and parasitic coupling. Details of the device design and fabrication, along with sensor performance characteristics, are presented and discussed.

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