Characterization of Al2O3/4H-SiC and Al2O3/SiO2/4H-SiC MOS structures

• Published in: Bulletin of the Polish Academy of Sciences. Technical sciences 2016-09, Vol.64 (3), p.547-551
• Main Authors: Taube, A., Guziewicz, M., Kosiel, K., Gołaszewska-Malec, K., Król, K., Kruszka, R., Kamińska, E., Piotrowska, A.
• Format: Article
• Language: English
• Subjects: 4H-SiC; aluminum oxide; high-κ dielectrics; MOS; silicon carbide
• ISSN: 2300-1917; 0239-7528; 2300-1917
• DOI: 10.1515/bpasts-2016-0061

The paper presents the results of characterization of MOS structures with aluminum oxide layer deposited by ALD method on silicon carbide substrates. The effect of the application of thin SiO buffer layer on the electrical properties of the MOS structures with Al layer has been examined. Critical electric field values at the level of 7.5–8 MV/cm were obtained. The use of 5 nm thick SiO buffer layer caused a decrease in the leakage current of the gate by more than two decade of magnitude. Evaluated density of trap states near the conduction band of silicon carbide in Al /4H-SiC MOS is about of 1×10 eV cm . In contrast, the density of the trap states in the Al /SiO /4H-SiC structure is lower about of one decade of magnitude 1×10 eV cm . A remarkable change in the MOS structure is also a decrease of density of electron traps located deeply in the 4H-SiC conduction band below detection limit due to using of the SiO buffer layer.