n型6H-SiCに対する化学エッチングおよび電極形成 : 結晶面方位依存性

概要

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We investigated how the crystallographic face polarity in n-type 6H-SiC affects the chemical etching rates, Schottky barrier heights, and specific contact resistance. A solution of HF: HNO_3 (1:1) chemically attacked only the (0001) Si-faced material after exposure to an artificial quartz lump. The etching was diffusion limited and the etched depth increased in proportion to the square root of the etching time. The Ni Schottky barrier heights were larger for the (0001) Si-face than for the (0001^^-) C-face. The specific contact resistance values of the Ni/6H-SiC (n-type) ohmic contacts formed on (0001) Si-faced and (0001^^-) C-faced materials were 5〜9 x 10^<・4> Ω・cm^2 and 7〜10 x 10^<・5> Ω・cm^2, respectively. Severe oxygen contamination was observed in the Ni/(0001) Si-face ohmic contacts, whereas oxygen was detected only on the uppermost metal surface of the Ni/(0001^^-) C-face ohmic contacts. We presumed that oxygen played an important role in forming Schottky barrier and the ohmic contacts.
2004-02-27