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Stoichiometry of the ALD-Al2O3/4H-SiC interface by synchrotron-based XPS
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits. Quaid I Azam Univ, Pakistan.
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
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2016 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 49, no 25, 255308Article in journal (Refereed) Published
Resource type
Text
Abstract [en]

The interface of Al2O3 with 4H-SiC is investigated with synchrotron-based high-resolution x-ray photoelectron spectroscopy to clarify the effect of post-dielectric deposition annealing processes (rapid thermal annealing (RTA) and furnace annealing (FA)) involved in device fabrication. Our results show that post-deposition annealing of Al2O3/4H-SiC up to 1100 degrees C forms a thin interfacial layer of SiO2 between Al2O3 and SiC, which possibly improves the dielectric properties of the system by reducing oxide charges and near-interface traps. Moreover, the formation of SiO2 at the interface gives additional band offset to the dielectric system. We have also observed that the RTA and FA processes have similar results at a high temperature of 1100 degrees C. Therefore, we propose that high-temperature post-oxide (Al2O3) deposition annealing of up to 1100 degrees C may be used in device processing, which can improve overall dielectric properties and consequently the device performance.

Place, publisher, year, edition, pages
2016. Vol. 49, no 25, 255308
Keyword [en]
4H-SiC, Al2O3, atomic layer deposition, annealing, interface, synchrotron radiation, XPS
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-189801DOI: 10.1088/0022-3727/49/25/255308ISI: 000378089600020Scopus ID: 2-s2.0-84976394351OAI: oai:DiVA.org:kth-189801DiVA: diva2:949621
Funder
Swedish Research Council, D0674701Swedish Foundation for Strategic Research
Note

QC 20160721

Available from: 2016-07-21 Created: 2016-07-15 Last updated: 2017-01-17Bibliographically approved
In thesis
1. Radiation Hardness of 4H-SiC Devices and Circuits
Open this publication in new window or tab >>Radiation Hardness of 4H-SiC Devices and Circuits
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Advances in space and nuclear technologies are limited by the capabilities of the conventional silicon (Si) electronics. Hence, there is a need to explore materials beyond Si with enhanced properties to operate in extreme environments. In this regards, silicon carbide (4H-SiC), a wide bandgap semiconductor, provides suitable solutions. In this thesis, radiation effects of 4H-SiC bipolar devices, circuits and dielectrics for SiC are investigated under various radiation types. We have demonstrated for the first time the radiation hardness of 4H-SiC logic circuits exposed to extremely high doses (332 Mrad) of gamma radiation and protons. Comparisons with previously available literature show that our 4H-SiC bipolar junction transistor (BJT) is 2 orders of magnitude more tolerant under gamma radiation to existing Si-technology. 4H-SiC devices and circuits irradiated with 3 MeV protons show about one order of magnitude higher tolerance in comparison to Si.

Numerical simulations of the device showed that the ionization is most influential in the degradation process by introducing interface states and oxide charges that lower the current gain. Due to the gain reduction of the BJT, the voltage reference of the logic circuit has been affected and this, in turn, degrades the voltage transfer characteristics of the OR-NOR gates.

One of the key advantages of 4H-SiC over other wide bandgap materials is the possibility to thermally grow silicon oxide (SiO2) and process device in line with advanced silicon technology. However, there are still questions about the reliability of SiC/SiO2 interface under high power, high temperature and radiation rich environments. In this regard, aluminium oxide (Al2O3), a chemically and thermally stable dielectric, has been investigated. It has been shown that the surface cleaning treatment prior to deposition of a dielectric layer together with the post dielectric annealing has a crucial effect on interface and oxide quality. We have demonstrated a new method to evaluate the interface between dielectric/4H-SiC utilizing an optical free carrier absorption technique to quantitative measure the charge carrier trapping dynamics. The radiation hardness of Al2O3/4H-SiC is demonstrated and the data suggests that Al2O3 is better choice of dielectric for devices in radiation rich applications.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2017. 56 p.
Series
TRITA-ICT, 2017:04
Keyword
Silicon carbide, radiation hardness, protons, gamma radiation, bipolar junction transistors, aluminium oxide, surface recombination.
National Category
Engineering and Technology
Research subject
Information and Communication Technology
Identifiers
urn:nbn:se:kth:diva-199907 (URN)978-91-7729-252-4 (ISBN)
Public defence
2017-02-17, Ka-Sal C (Sal Sven-Olof Öhrvik), KTH, Kistagången 16, Kista, 10:00 (English)
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Note

QC 20170119

Available from: 2017-01-19 Created: 2017-01-17 Last updated: 2017-01-19Bibliographically approved

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