Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Investigation of Current Gain Degradation in 4H-SiC Power BJTs
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
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: 0000-0001-6459-749X
Show others and affiliations
2012 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 717-720, 1131-1134 p.Article in journal (Refereed) Published
Abstract [en]

The current gain degradation of 4H-SiC BJTs with no significant drift of the on-resistance is investigated. Electrical stress on devices with different emitter widths suggests that the device design can influence the degradation behavior. Analysis of the base current extrapolated from the Gummel plot indicates that the reduction of the carrier lifetime in the base region could be the cause for the degradation of the gain. However, analysis of the base current of the base-emitter diode shows that the degradation of the passivation layer could also influence the reduction of the current gain.

Place, publisher, year, edition, pages
2012. Vol. 717-720, 1131-1134 p.
Keyword [en]
4H-SiC, BJT, degradation, current gain, temperature
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-95318DOI: 10.4028/www.scientific.net/MSF.717-720.1131ISI: 000309431000270Scopus ID: 2-s2.0-84861349620OAI: oai:DiVA.org:kth-95318DiVA: diva2:527735
Conference
14th International Conference on Silicon Carbide and Related Materials 2011, ICSCRM 2011; Cleveland, OH;11 September 2011 through 16 September 2011
Funder
StandUp
Note

QC 20120522

Available from: 2012-05-22 Created: 2012-05-22 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Simulation and Characterization of Silicon Carbide Power Bipolar Junction Transistors
Open this publication in new window or tab >>Simulation and Characterization of Silicon Carbide Power Bipolar Junction Transistors
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The superior characteristics of silicon carbide, compared with silicon, have suggested considering this material for the next generation of power semiconductor devices. Among the different power switches, the bipolar junction transistor (BJT) can provide a very low forward voltage drop, a high current capability and a fast switching speed. However, in order to compete on the market, it is crucial to a have high current gain and a breakdown voltage close to ideal. Moreover, the absence of conductivity modulation and long-term stability has to be solved.

In this thesis, these topics are investigated comparing simulations and measurements. Initially, an efficient etched JTE has been simulated and fabricated. In agreement with the simulations, the fabricated diodes exhibit the highest BV of around 4.3 kV when a two-zone JTE is implemented. Furthermore, the simulations and measurements demonstrate a good agreement between the electric field distribution inside the device and the optical luminescence measured at breakdown.

Additionally, an accurate model to simulate the forward characteristics of 4H-SiC BJTs is presented. In order to validate the model, the simulated current gains are compared with measurements at different temperatures and different base-emitter geometries. Moreover, the simulations and measurements of the on-resistance are compared at different base currents and different temperatures. This comparison, coupled with a detailed analysis of the carrier concentration inside the BJT, indicates that internal forward biasing of the base-collector junction limits the BJT to operate at high current density and low forward voltage drop simultaneously. In agreement with the measurements, a design with a highly-doped extrinsic base is proposed to alleviate this problem.

In addition to the static characteristics, the comparison of measured and simulated switching waveforms demonstrates that the SiC BJT can provide fast switching speed when it acts as a unipolar device. This is crucial to have low power losses during transient.

Finally, the long-term stability is investigated. It is observed that the electrical stress of the base-emitter diode produces current gain degradation; however, the degradation mechanisms are still unclear. In fact, the analysis of the measured Gummel plot suggests that the reduction of the carrier lifetime in the base-emitter region might be only one of the causes of this degradation. In addition, the current gain degradation due to ionizing radiation is investigated comparing the simulations and measurements. The simulations suggest that the creation of positive charge in the passivation layer can increase the base current; this increase is also observed in the electrical measurements.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. xiv, 82 p.
Series
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2012:08
Keyword
silicon carbide, power device, BJT, diode, simulation, characterization, current gain, on-resistance, breakdown voltage, forward voltage drop, degradation
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
SRA - ICT
Identifiers
urn:nbn:se:kth:diva-95320 (URN)978-91-7501-365-7 (ISBN)
Public defence
2012-06-08, C1, Electrum, KTH-ICT, Isafjordsgatan 26, Kista, 10:00 (English)
Opponent
Supervisors
Note
QC 20120522Available from: 2012-05-22 Created: 2012-05-22 Last updated: 2012-05-22Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Authority records BETA

Malm, GunnarZetterling, Carl-Mikael

Search in DiVA

By author/editor
Buono, BenedettoGhandi, RezaDomeij, MartinMalm, GunnarZetterling, Carl-MikaelÖstling, Mikael
By organisation
Integrated Devices and Circuits
In the same journal
Materials Science Forum
Electrical Engineering, Electronic Engineering, Information Engineering

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 135 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf