In-situ observation of nitriding processes of evaporated-Ti thin films due to ion implantation in an analytical transmission electron microscope

窒素イオン注入による蒸着チタン膜の窒化過程の分析電子顕微鏡によるその場観察

粕壁 善隆*; Chen, Y.*; 山本 春也; 吉川 正人; 藤野 豐*

Kasukabe, Yoshitaka*; Chen, Y.*; Yamamoto, Shunya; Yoshikawa, Masahito; Fujino, Yutaka*

本研究では、TIARA施設のイオン導入型電子顕微鏡を用いて、窒素イオン注入法によるチタン窒化物の形成を行い、透過電子顕微鏡(TEM)及び電子エネルギー損失分光(ELLS)による結晶構造及び電子状態のその場観察を行うとともに、分子軌道計算による電子状態の理論解析を進め、原子レベルでのチタン窒化物の形成機構を調べた。窒素イオン注入時のチタン膜試料の温度を変えて実験観察を進めその解析を行った結果、イオン注入によってチタン膜中に導入される窒素の濃度やその電子構造が注入時の試料温度によって変化することがわかった。

The purpose of this work is to study changes of the crystallographic and electronic structures of Ti films by heating and by nitriding during N-implantation into Ti films, using in-situ transmission electron microscope equipped with the instrument for electron energy loss spectroscopy, and then to clarify the atomistic nitriding processes of Ti thin films due to the N-implantation with the aid of self-consistent charge discrete variational X molecular orbital calculations. It is clarified that the maximum concentration of N in Ti films during the N-implantation and the change of electronic structures near the fermi level, respectively, depend on the implantation temperature and the ratio of N/Ti in Ti films. Furthermore, taking into account the bonding interaction of Ti sublattices with ligand N atoms, the transformation mechanisms between hcp-Ti and fcc-Ti sublattices due to the implantation of N atoms are discussed.