Temperature Modeling and Characterization of the Current Gain in 4H-SiC Power BJTs
2010 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 645-648, 1061-1064 p.Article in journal (Refereed) Published
The current gain of 4H-SiC BJTs has been modeled using interface traps between SIC and SiO2 to describe surface recombination, by a positive temperature dependence of the carrier lifetime in the base region and by bandgap narrowing in the emitter region. The interface traps have been modeled by one single level at 1 eV above the valence band, with capture cross section of 1 x 10(-15) cm(2) and concentration of 2 x 10(12) cm(-2). The temperature behavior of SiC BJTs has been simulated and the results have been compared with measurements. An analysis of the carrier concentration has been performed in order to describe the mechanisms for fall-off of the current gain at high collector current. At room temperature high injection in the base and forward biasing of the base-collector junction occur simultaneously causing an abrupt drop of the current gain. At higher temperatures high injection in the base is alleviated by the higher ionization degree of the aluminum dopants, and then forward biasing of the base-collector junction is the only acting mechanism for the current gain fall-off at high collector current. This mechanism and the negative temperature dependence of the carrier mobility can also explain the reduction of the knee current for gain fall-off with increasing temperature. Simulations with different emitter widths have been also performed and analyzed to characterize the emitter size effect. Higher current density caused by reducing the emitter width introduces higher carrier recombination in the emitter region, leading to a reduction of the current gain.
Place, publisher, year, edition, pages
Trans Tech Publications Inc., 2010. Vol. 645-648, 1061-1064 p.
simulations, current gain, interface traps, temperature modeling, emitter size effect
Other Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:kth:diva-29828DOI: 10.4028/www.scientific.net/MSF.645-648.1061ISI: 000279657600253ScopusID: 2-s2.0-77955437970OAI: oai:DiVA.org:kth-29828DiVA: diva2:398297
13th International Conference on Silicon Carbide and Related Materials, Nurnberg, GERMANY, OCT 11-16, 2009
QC 201102172011-02-172011-02-172016-05-11Bibliographically approved