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

Abstract

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

Topics

• Deposition
• density
• impedance spectroscopy
• surface
• semiconductor
• etching
• defect
• annealing