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Effect of nuclear scattering damage at the SiO2/SiC and Al2O3/SiC interface: A radiation hardness study of dielectrics
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.ORCID iD: 0000-0002-8760-1137
Vilnius University, Lithuania.
Vilnius University, Lithuania.
2012 (English)In: Silicon Carbide And Related Materials 2011, Pts 1 And 2, Trans Tech Publications Inc., 2012, Vol. 717-720, 805-808 p.Conference paper, Published paper (Refereed)
Abstract [en]

The radiation hardness of Al2O3 as a dielectric for SiC surface passivation is studied and compared to SiO2 for potential application in radiation hard SiC devices. SiO2 is deposited on 4H-SiC by PECVD and post annealed in N2O, whereas Al2O3 is deposited by atomic layer deposition (ALD). The oxides are bombarded with Ar ions in an energy range to produce maximum damage near the oxide/SiC interface. Metal-insulator-semiconductor structures are prepared and their dielectric characteristics are analyzed using capacitance-voltage measurements. Additionally, the effect of the interface damage on surface recombination is studied using the optical free carrier absorption method for the same samples. The results indicate that the SiO2/SiC interface is significantly affected at 1×1011 cm-2 fluence of Ar ions, however, the dielectric properties of Al2O3/SiC interface remain unaffected even for ten times higher fluences. Similar observations are made for the surface recombination measurements.

Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2012. Vol. 717-720, 805-808 p.
Series
Materials Science Forum, ISSN 0255-5476 ; 717-720
Keyword [en]
4H-SiC, High-k Dielectrics, Interface Damage, MIS, Radiation Hardness
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-61428DOI: 10.4028/www.scientific.net/MSF.717-720.805ISI: 000309431000191Scopus ID: 2-s2.0-84861374648OAI: oai:DiVA.org:kth-61428DiVA: diva2:479074
Conference
14th International Conference on Silicon Carbide and Related Materials 2011, ICSCRM 2011; Cleveland, OH;11 September 2011 through 16 September 2011
Note

QC 20120806

Available from: 2012-01-17 Created: 2012-01-17 Last updated: 2013-09-12Bibliographically approved
In thesis
1. Impact of Ionizing Radiation on 4H-SiC Devices
Open this publication in new window or tab >>Impact of Ionizing Radiation on 4H-SiC Devices
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electronic components, based on current semiconductor technologies and operating in radiation rich environments, suffer degradation of their performance as a result of radiation exposure. Silicon carbide (SiC) provides an alternate solution as a radiation hard material, because of its wide bandgap and higher atomic displacement energies, for devices intended for radiation environment applications. However, the radiation tolerance and reliability of SiC-based devices needs to be understood by testing devices  under controlled radiation environments. These kinds of studies have been previously performed on diodes and MESFETs, but multilayer devices such as bipolar junction transistors (BJT) have not yet been studied.

In this thesis, SiC material, BJTs fabricated from SiC, and various dielectrics for SiC passivation are studied by exposure to high energy ion beams with selected energies and fluences. The studies reveal that the implantation induced crystal damage in SiC material can be partly recovered at relatively low temperatures, for damag elevels much lower than needed for amorphization. The implantation experiments performed on BJTs in the bulk of devices show that the degradation in deviceperformance produced by low dose ion implantations can be recovered at 420 oC, however, higher doses produce more resistant damage. Ion induced damage at the interface of passivation layer and SiC in BJT has also been examined in this thesis. It is found that damaging of the interface by ionizing radiation reduces the current gain as well. However, for this type of damage, annealing at low temperatures further reduces the gain.

Silicon dioxide (SiO2) is today the dielectric material most often used for gate dielectric or passivation layers, also for SiC. However, in this thesis several alternate passivation materials are investigated, such as, AlN, Al2O3 and Ta2O5. These materials are deposited by atomic layer deposition (ALD) both as single layers and in stacks, combining several different layers. Al2O3 is further investigated with respect to thermalstability and radiation hardness. It is observed that high temperature treatment of Al2O3 can substantially improve the performance of the dielectric film. A radiation hardness study furthermore reveals that Al2O3 is more resistant to ionizing radiation than currently used SiO2 and it is a suitable candidate for devices in radiation rich applications.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. iv, 71 p.
Series
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2012:02
Keyword
Silicon carbide, ionizing radiation, bipolar junction transistors, reliability, surface passivation, high-k dielectrics, MIS, radiation hardness
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-60763 (URN)978-91-7501-225-4 (ISBN)
Public defence
2012-02-03, Sal C1, KTH-Electrum, Isafjordsgatan 22, Kista, 10:00 (English)
Opponent
Supervisors
Note
QC 20120117Available from: 2012-01-17 Created: 2012-01-14 Last updated: 2012-01-17Bibliographically approved

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