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Position dependent traps and carrier compensation in 4H-SiC bipolar junction transistors
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
(English)In: IEEE Transactions on Electron Devices, ISSN 0018-9383Article in journal (Other academic) Submitted
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-61419OAI: diva2:479063
QS 20120328Available from: 2012-01-17 Created: 2012-01-17 Last updated: 2012-03-28Bibliographically 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

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