Development of Pure Siliconcarbide for Highvoltage Powerelectronic Applications

Purpose and goal

The ambition with this prestudy has been to investigate whether the SiC HTCVD substrat produced by Norstel Ab can be directly used as avtive layer in high voltage application. This requires that the C-vacances and C-vacancecluster, which are created at the high growth temperature (>2000 C), can be neutralized. This is done by C-ionimplanation followed by a high temperat annealing, where C-interstitials are diffusing and neutralize the c-vacances.

Expected results and effects

Using C-ionimplantation and high temperature annealing has been show to reduce C-vacancy density in thick epitaxial layers where only single C-vacancies are present due to the lower growth temperature (~1650 C). This has been seen as a reduction of the carrier lifetime which is limited by the C-vacancy. In the HTCVD substrates we did not achieve the same effect, probably due to the presence of C-vacancyclusters.

Planned approach and implementation

Based on the limited resources and time for the prestudy, theuse of existing HTCVD substrates were reasonable. The ionimplantation and annealing was a succesful process, as seen by the result in the thick epitaxial layers. A continuationof the Project must however also include development of the HTCVD substrates to further reduce residual impurities.