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Fabrication of Ge Metal–Oxide–Semiconductor Capacitors with High-Quality Interface by Ultrathin SiO 2 /GeO 2 Bilayer Passivation and Postmetallization Annealing Effect of Al

2011; Institute of Physics; Volume: 50; Issue: 4S Linguagem: Inglês

10.1143/jjap.50.04da10

1347-4065

Kana Hirayama, Ryuji Ueno, Yoshiaki Iwamura, Keisuke Yoshino, Dong Wang, Haigui Yang, Hiroshi Nakashima,

Semiconductor materials and interfaces

A novel method of electrical passivation of a Ge surface by an ultrathin SiO 2 /GeO 2 bilayer is proposed as an effective method for fabricating metal–oxide–semiconductor (MOS) structures, which can be processed through the thermal etching of GeO 2 by vacuum annealing and subsequent SiO 2 deposition. We demonstrated the feasibility of this passivation technique by performing interface state density ( D it ) measurements of MOS capacitors, which were fabricated using several surface preparations and subsequent gate insulating film deposition. A D it of 4×10 11 cm -2 eV -1 was obtained at around midgap. We also investigated the effect of postmetallization annealing after Al deposition (Al-PMA). Al-PMA was found to be very effective for decreasing D it , which was 9.4×10 10 cm -2 eV -1 at around midgap for a capacitor with PMA at 400 °C. The role of Al as a defect terminator was discussed.