Fabrication of single boundary electroceramic devices controlled by localized quantum structure at boundaries

在大多数电陶瓷材料中，经常使用在晶界处形成的双肖特基势垒来获得独特的电学性能。例如，实用的器件，如正电阻率温度系数（PTCR）器件和可变器件使用双肖特基势垒（DSB）给出的电性能。一般来说，DSB的电学性质是由晶界界面态的电子捕获形成的。因此，为了理解和开发高质量的器件，有必要通过使用单一边界现象（例如双晶体等污染良好的样品）的系统研究来阐明界面状态的起源。本研究旨在揭示晶界原子结构与其电学性能之间的关系，进而实现单晶界器件的制备。材料采用nb掺杂SrTiO3和ZnO。在小的倾斜角度范围内，所有的晶界都由晶界位错组成。此外，在这种晶界处观察到的电流-电压特性的非线性显示出倾斜角依赖性。即，DSB的高度与晶界位错的密度密切相关。通过详细研究，非线性在约10度边界处最大。这可能是因为该边界具有一组特殊的晶界位错。同时，在ZnO双晶中，没有任何非晶相的掺pr ZnO双晶具有较大的非线性。

In most of electroceramic materials, double Schottky barriers formed at grain boundaries are often used to obtain unique electrical properties. For example, practical devices such as positive temperature coefficient of resistivity (PTCR) devices and varistic one use the electrical properties given by double Schottky barriers (DSB). In general, the electrical properties of DSB are formed by electrons trapped at interface states at grain boundaries. So, to understand and to develop high quality devices, it is necessary to clarify an origin of the interface state by systematic investigation using single boundary phenomena, for example, well-defiled samples such as bicrystals. This study aimed to reveal relationships between grain boundary atomic structure and its electrical properties, and further, to fabricate devices with single grain boundary. Nb-doped SrTiO3 and ZnO were used for materials. In a range of small tilt angles, all of the boundaries are consisting of grain boundary dislocations. In addition, non-linearity observed in current-voltage property at such grain boundaries was found to show a tilt angle dependency. Namely, a height of DSB is closely related to a density of grain boundary dislocations. By detail investigation, non-linearity becomes largest at about 10degress boundary. This may be because that boundary has a special array of grain boundary dislocations. Meanwhile, in ZnO bicrystals, large non-linearity could be obtained in Pr-doped ZnO bicrystals without any amorphous phases.