Electrical characterization of amorphous Al2O3 dielectric films on n-type 4H-SiC
Journal article, 2018

We report on the electrical properties of Al 2 O 3 films grown on 4H-SiC by successive thermal oxidation of thin Al layers at low temperatures (200°C - 300°C). MOS capacitors made using these films contain lower density of interface traps, are more immune to electron injection and exhibit higher breakdown field (5MV/cm) than Al 2 O 3 films grown by atomic layer deposition (ALD) or rapid thermal processing (RTP). Furthermore, the interface state density is significantly lower than in MOS capacitors with nitrided thermal silicon dioxide, grown in N 2 O, serving as the gate dielectric. Deposition of an additional SiO 2 film on the top of the Al 2 O 3 layer increases the breakdown voltage of the MOS capacitors while maintaining low density of interface traps. We examine the origin of negative charges frequently encountered in Al 2 O 3 films grown on SiC and find that these charges consist of trapped electrons which can be released from the Al 2 O 3 layer by depletion bias stress and ultraviolet light exposure. This electron trapping needs to be reduced if Al 2 O 3 is to be used as a gate dielectric in SiC MOS technology.

Author

Rabia Y. Khosa

University of Iceland

E. B. Thorsteinsson

University of Iceland

Michael Winters

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Niklas Rorsman

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Robin Karhu

Linköping University

J. Hassan

Linköping University

E. O. Sveinbjornsson

University of Iceland

Linköping University

AIP Advances

2158-3226 (ISSN)

Vol. 8 2 025304

Subject Categories

Inorganic Chemistry

Materials Chemistry

Condensed Matter Physics

DOI

10.1063/1.5021411

More information

Latest update

4/20/2018