Shallow donor level associated with hydrogen impurities in undoped BaTiO

アンドープBaTiOにおける水素不純物に関連した浅いドナー準位

伊藤 孝   ; 髭本 亘  ; 松田 達磨*; 幸田 章宏*; 下村 浩一郎*

Ito, Takashi; Higemoto, Wataru; Matsuda, Tatsuma*; Koda, Akihiro*; Shimomura, Koichiro*

The influence of hydrogen impurities on electronic properties of undoped BaTiO was studied from a microscopic point of view using the muon spin rotation and relaxation technique. Electron localization around an implanted positive muon, by analogy an hydrogen impurity, was observed below 80 K. The effective electron binding energy was estimated to be eV, indicating that the hydrogen-induced defect forms a shallow donor level. At room temperature, the weakly bound electron is excited into a conduction band and behaves as a free carrier, which causes insulation degradation undesirable for capacitor application.