liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
a-Si:H photodiodes in vision applications
Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
Linköping University, Department of Electrical Engineering, Electronic Devices. Linköping University, The Institute of Technology.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Advanced CMOS machine vision chips with in-pixel processing capability suffer from trade-offs in CMOS diode area vs processing circuitry. The benefit to use hydrogenated amorphous silicon (a-Si:H) diodes post-processed on the CMOS chip is both area gain and in some spectral regions increased sensitivity. Diode characteristics such as short transient response and image lag, related to machine vision application requirements are treated. Measured transient response to illumination pulses resulted in rise and fall times of shortest 2-3 S and around 7 μS respectively. The same diodes did also give longer rise times of around 30 μS, and the possible causes of the instability are discussed. Image lag was measured as an increased dark current following illumination turn-off, and was found to be small, below 50% of the very low dark current, bias-dependent and not correlated to illumination intensity. The possible influence on imager performance is discussed.

National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-87088OAI: oai:DiVA.org:liu-87088DiVA: diva2:584952
Available from: 2013-01-09 Created: 2013-01-09 Last updated: 2013-01-09
In thesis
1. Photo diodes for machine vision: device characteristics and a-Si:H deposition and analysis
Open this publication in new window or tab >>Photo diodes for machine vision: device characteristics and a-Si:H deposition and analysis
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

During the last years the area of digital cameras based on CMOS technology has grown rapidly. In CMOS, signal processing circuitry and sensor elements can be combined on the same chip, which has resulted in advanced machine vision chip designs. However, the potentially powerful combination of diodes and in-pixel signal processing circuitry, suffers from problems of area utilization trade-offs. By using hydrogenated amorphous silicon (a-Si:H) diodes that are post-processed on the CMOS chip we can achieve a number of advantages. They are better with respect to area utilization and in some sense avoid problems like bulk wafer defects. In addition the evolution of CMOS processes is moving in a direction that degrades the properties of sensor elements.

This thesis explores photo diodes made of a-Si:H with a special focus on fabrication methods and device characteristics for machine vision applications. The work includes characterization of state-of-the-art diodes describing their lag current, photo current rise and fall time, and stability. To further explain themeasured characteristics a device model based on the physical semiconductor material properties has been developed.

This thesis also explores the use of de magnetron sputter deposition as a fabrication method for the a-Si:H p-i-n diodes. The impurity incorporation for the p- and n-doped layers was accomplished using doped targets. This technique is unusual and required a particular research effort. Dielectric functions for the intrinsic as well as n- and p-doped films were extracted and used to predict the optical properties of a p-i-n diode.

The conclusion of this research project is that a-Si:H diodes are suitable for machine vision chips.

Place, publisher, year, edition, pages
Linköping: Linköping studies in science and technology, 2003. 40 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 799
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-34896 (URN)23851 (Local ID)91-7373-602-3 (ISBN)23851 (Archive number)23851 (OAI)
Public defence
2003-03-21, Sal Visionen, Linköpings Universitet, Linköping, 10:15 (Swedish)
Opponent
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-01-09

Open Access in DiVA

No full text

Authority records BETA

Rantzer, AnnikaSvensson, Christer

Search in DiVA

By author/editor
Rantzer, AnnikaSvensson, Christer
By organisation
Electronic DevicesThe Institute of Technology
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 52 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf