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Sputter-deposited a-Si:H for p-i-n photodiodes
Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
Department of Physics, Uppsala University, Uppsala, Sweden.
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.ORCID iD: 0000-0001-9140-6724
IBM TJ Watson Research Center, Yorktown Heights, NY, USA.
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

DC magnetron sputter deposition is explored as an alternative for fabricating vertically integrated sensor systems in the form of p-i-n diodes of hydrogenated amorphous silican deposited on CMOS integrated circuit substrates in a post-processing step. We focus here on dopant oncorporation and surface morphological evolution during synthesis of the p-i-n diode sensor structures. The Doping was accomplished using doped targets in a mixed H2/Ar environment. Incorporated P concetrations range from 2.62 to 4.8 x 1019 cm-3 with corresponding conductivities, σ, up to 1.4 x10-5 ohm-1cm-1. B contentrations are between 2.79 and 6.7 X 1020 cm-3 with σ = 4 x 10-5 to 4 x 10-2 ohm-1cm-1. The results of the dopant incorporation are in agreement with reported molecular dynamics simulations. The best intrinsic films have a light to dark conductivity ratio of 102 for white light at an intensity of 10 W/m2. The dark conductivity is a 8 x 10-9 ohm-1cm-1. We conclude that dc magnetron sputter deposition is a good candidate for future device fabrication.

National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-87085OAI: diva2:584885
Available from: 2013-01-09 Created: 2013-01-09 Last updated: 2015-03-09
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.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 799
National Category
Engineering and Technology
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)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-01-09

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Rantzer, AnnikaPersson, Per O. A.Järrendahl, KennethArwin, Hans
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