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Vacancy-type defects in TiO2/SiO2/SiC dielectric stacks

Lookup NU author(s): Dr Rajat Mahapatra, Professor Nick Wright


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Open-volume (vacancy-type) point defects have been observed in ∼80-nm -thick titanium dioxide films grown on silicon dioxide 4H silicon carbide substrates as stacks with high dielectric constant for power device applications, using variable-energy positron annihilation spectroscopy. The concentration of vacancies decreases as the titanium dioxide growth temperature is increased in the range from 700 to 1000 °C, whereas grain boundaries form in the polycrystalline material at the highest growth temperatures. It is proposed that the optimal electrical performance for films grown at 800 °C reflects a balance between decreasing vacancy concentration and increasing grain boundary formation. The concentration of vacancies at the silicon dioxidesilicon carbide interface appears to saturate after 2.5 h oxidation at 1150 °C. A supplementary result suggests that the quality of the 10-μm -thick deposited silicon carbide epilayer is compromised at depths of about 2 μm and beyond, possibly by the migration of impurities andor other defects from the standard-grade highly doped 4H silicon carbide wafer beneath the epilayer during oxidation. © 2007 American Institute of Physics.

Publication metadata

Author(s): Coleman PG, Burrows CP, Mahapatra R, Wright NG

Publication type: Article

Publication status: Published

Journal: Journal of Applied Physics

Year: 2007

Volume: 102

Issue: 1

ISSN (print): 0021-8979

ISSN (electronic): 1089-7550

Publisher: American Institute of Physics


DOI: 10.1063/1.2752129


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