Change search
ReferencesLink to record
Permanent link

Direct link
Toward the Understanding of Stacked Al-Based High-k Dielectrics for Passivation of 4H-SiC Devices
KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.ORCID iD: 0000-0002-8760-1137
Show others and affiliations
2011 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, Vol. 158, no 1, H75-H79 p.Article in journal (Refereed) Published
Abstract [en]

Metal insulator semiconductor structures using high-k materials have been prepared and investigated for the passivation of 4H-SiC surfaces. Alternate layers of AlN and Al2O3 were deposited on 8 nm thermally grown SiO2 on epitaxial SiC, forming multilayer stacked dielectrics. Atomic layer deposition (ALD) has been used for the deposition. Our results show that the AlN, deposited by ALD, has a columnar polycrystalline structure with boundaries related to the step bunching of SiC epitaxial layer. Capacitance-voltage measurements have been performed at room temperature, 100, 200, and 300 degrees C. Annealing of the samples was also performed at these temperatures and they were consecutively measured at room temperature. Current-voltage measurements have also been performed before and after annealing. It has been observed that the stack with a bottom layer of Al2O3, forming an interface with the thin SiO2, is more stable at high temperatures; however, its breakdown voltage is less than that of the other stack with AlN forming the bottom layer. The breakdown behavior of the stacks is also found to be different depending on the order of AlN and Al2O3 layers.

Place, publisher, year, edition, pages
2011. Vol. 158, no 1, H75-H79 p.
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-27675DOI: 10.1149/1.3517137ISI: 000284697900050ScopusID: 2-s2.0-79951996830OAI: diva2:380665
QC 20101222Available from: 2010-12-22 Created: 2010-12-20 Last updated: 2012-01-17Bibliographically 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.
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2012:02
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
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)
QC 20120117Available from: 2012-01-17 Created: 2012-01-14 Last updated: 2012-01-17Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Usman, MuhammadHallén, Anders
By organisation
Microelectronics and Applied Physics, MAP
In the same journal
Journal of the Electrochemical Society
Electrical Engineering, Electronic Engineering, Information Engineering

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 51 hits
ReferencesLink to record
Permanent link

Direct link