Morimoto Yuka, Nishiyama Junji, Takeda Hiroaki, Tsurumi Takaaki, Hoshina Takuya
Nano-phononics Lab., School of Materials and Chemical Technology, Tokyo Institute of Technology, Ookayama, Meguro, Tokyo, 152-8552, Japan.
Sci Rep. 2018 Mar 22;8(1):5031. doi: 10.1038/s41598-018-23019-9.
A transparent semiconducting SrTiO single crystal with a resistivity of the order of 10 Ω·cm was fabricated by heating a SrTiO single crystal with gaseous ammonia and CeO powder. Conductive atomic force microscope (C-AFM) measurement revealed that micro-sized voids were formed and the high conductivity was exhibited only at around the voids. It is considered that the micro-sized voids were caused by the concentrated SrO planar defects, and TiO-terminated structure with oxygen vacancies contributed to the two-dimensional conduction. In the heating process, the CeO powder acted as an oxygen source, and radicals such as NH and NH were generated by the reaction of oxygen and ammonia. The radicals may have contributed to the formation of three-dimensional network of the conductive paths consisting of SrO planar defects without the reduction of the bulk components. The electrons were localized on the TiO-terminated structure, and the volume content of the conductive paths was small compared to the insulating bulk component. Therefore, the crystal was optically transparent and semiconducting.
通过用气态氨和CeO粉末加热SrTiO单晶制备出了电阻率约为10 Ω·cm的透明半导体SrTiO单晶。导电原子力显微镜（C-AFM）测量表明形成了微米级的空洞，并且仅在空洞周围表现出高导电性。据认为，微米级空洞是由集中的SrO平面缺陷引起的，具有氧空位的TiO端接结构有助于二维传导。在加热过程中，CeO粉末充当氧源，氧与氨反应生成NH和NH等自由基。这些自由基可能有助于由SrO平面缺陷组成的导电路径的三维网络的形成，而不会使体相成分减少。电子定域在TiO端接结构上，与绝缘的体相成分相比，导电路径的体积含量较小。因此，该晶体是光学透明且半导体性的。
