Preparation of transparent ZnO ceramic with Crystal-Axis Orientation and Development of Functional Materials Combining Piezo electric and Semiconducting Propertes

建立了高晶轴取向透明氧化锌晶体大样品(7 mm立方体)的制备工艺。这是通过使用晶体取向的氧化锌作为衬底和它的旋转实现的。考察了Li_2O掺杂对制备压电材料的影响。Li_2O的唯一方法是高温扩散。在样品表面涂上少量的LiCO_3，在800~900ﾟC下加热，可以有效地获得均匀的绝缘体。机电耦合常数强烈地依赖于轴的取向程度，而与轴的不均匀性关系不大。没有非(001)晶面X射线衍射峰的高晶轴取向样品，其电阻率高达100MOMEGA cm，表现出与文献报道的单晶相同的高机电耦合常数。光激发电流依赖于偏置电压及其施加方向，应用该方法建立了晶界模型。用这种方法制备的氧化锌沿生长方向有c轴择优取向。以A面或C面为衬底，采用两步生长法制备了边界清晰的样品。由此可见，氧对氧化锌晶界势垒的形成起着重要的作用。用所制备的样品讨论了晶格匹配对这种势垒的影响。在90K，具有C-C结的样品中观察到了势垒。具有晶格失配的C-A结的样品没有出现势垒。这一结果表明，在讨论势垒时，不仅要考虑过量氧，还要考虑Piezo效应。

The technique to obtain the large sample(7mm cube) of transparent ZnO crystal with high crystal-axis orientation has been established. That was attained by using a crystal oriented ZnO as a substrate and its rotation. The Li_2O doping was examined to prepare the Piezo electric material. The only method for Li_2O was the diffusion at high temperature. The small amount of LiCO_3 was painted on the surface of the sample and heated at 800-900ﾟC. The recicling this method was effective to obtain the homogeneous insulator. The electrical-mechanical coupling constant depended on the degree of axis orientation strongly and inhomogenity slightly. The high crystal axis oriented sample without the X-ray diffraction peak from other than (001) and with high resistivity to be 100MOMEGA cm showed high electrical-mechanical coupling constant same as the reported value of single crystal. The light excited current depended on the bias voltage and its applied direction.The grain boundary model was prepared by appling this method. The prepared ZnO by this method has a c-axis preferencial orientation along to the growth direction. The sample with clear boundary was prepared by using 2 step growth method with the A or C plane as the substrate. It is clear that oxygen plays an important role to develop the potential barrier along the ZnO grain boundary. This prepared sample was used to discuss the effect of lattice matching on such a barrier. The potential barrier was observed in the sample with C-C junction at 90K. The sample with C-A junction which has lattice mismatching did not show the potential barrier. This result suggest that we should discuss the potential barrier with considerration for not only the excess oxygen but also the Piezo effect.