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Interface analysis of p-type 4H-SiC/Al2O3 using synchrotron-based XPS
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
KTH, School of Information and Communication Technology (ICT).
KTH, School of Information and Communication Technology (ICT). Quaid-i-Azam University, Pakistan.
KTH, School of Information and Communication Technology (ICT).
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2016 (English)In: 16th International Conference on Silicon Carbide and Related Materials, ICSCRM 2015, Trans Tech Publications Ltd , 2016, p. 693-696Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, the interface between Al2O3 and p-type 4H-SiC is evaluated using x-ray photoelectron spectroscopy (XPS) measurements. These studies are made on dielectricsemiconductor test structures with Al2O3 as dielectric with different pre- and post-deposition treatments. XPS measurements on the as-deposited samples with two different pre-surface cleaning methods have shown no formation of a SiO2 interlayer. However, after the post deposition rapid thermal annealing (RTA) at 1100 °C in N2O for 60 s, a SiO2 interlayer is formed. The surface band bending was determined from Si 2p core level peak shifts measured using XPS. These results suggest that Al2O3 deposited on the p-type 4H-SiC have a net positive oxide charge which is complementary to that of Al2O3 on n-type 4H-SiC. From these shifts it was found that the asdeposited RCA cleaned sample had an oxide charge of 5.6×1013 cm-2, as compared to standard cleaned samples, having 4.6×1013 cm-2. A further reduction in oxide charge was observed after annealing at 1100 °C in N2O, down to a value of 4×1013 cm-2.

Place, publisher, year, edition, pages
Trans Tech Publications Ltd , 2016. p. 693-696
Keywords [en]
Al2O3, Band bending, P-type 4H-SiC, X-ray photoelectron spectroscopy (XPS), Aluminum, Core levels, Deposition, Photoelectrons, Photons, Rapid thermal annealing, Silicon carbide, Silicon oxides, Surface cleaning, Bandbending, Core-level peaks, Interface analysis, Post deposition treatment, Rapid thermal annealing (RTA), Surface band bending, XPS measurements, X ray photoelectron spectroscopy
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-195522DOI: 10.4028/www.scientific.net/MSF.858.693Scopus ID: 2-s2.0-84971570052ISBN: 9783035710427 (print)OAI: oai:DiVA.org:kth-195522DiVA, id: diva2:1049693
Conference
4 October 2015 through 9 October 2015
Note

QC 20161125

Available from: 2016-11-25 Created: 2016-11-03 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. p. 56
Series
TRITA-ICT ; 2017:04
Keywords
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)
Opponent
Supervisors
Note

QC 20170119

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

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Hallén, Anders

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