Quantum Well Effects in Ionic Insulators and Metals.

在1986年发现交替KCI-KBr多层结构的吸收光谱上KBr激子带的量子尺寸效应后，我们主要研究了几种碱卤化物中的量子阱激子，积累了大量的相关知识。这些知识简述如下。在KCI-KBr或RbCl-xBr多层结构的吸收光谱中出现能量最低的阱激子带（KBr）表现出蓝移的影响，有两种效应，即量子约束导致激子动力学的增加和界面混合物形成导致阱带隙的增加。而激子波函数的约束即使在激子波半径宽10倍的阱中也有效地发生，并且似乎使激子带的上升幅度明显增大。在适当的温度下逐层热退火可以降低层间界面混合对非退火多层材料中明显的蓝移的影响，实现了无界面失配和无界面混合结构。界面混合物的形成强烈依赖于退火温度和蒸发速度，目前认为温度为180 ~ 200 C，蒸发速度小于1A^^ /sec有利于界面混合物的形成。它还揭示，如果。由于薄膜与衬底晶体之间的晶格常数存在较大的差异，在小于100A^^的极薄薄膜情况下，界面失配效应很重要。近期，将在刚刚建成的实验室内对薄层的热退火条件和蒸发速度进行研究。

After discovery of the quantum size effect in the KBr exciton band on the absorption spectra of alternate KCI-KBr multilayer structure in 1986, we have mainly investigated the quantum well excitons in several alkali halides and accumulated lots of knowledges on them. These knowledges are briefly explained as the follows.The exciton band due to the well (KBr) which appears at the lowest energy on the absorption spectra of KCI-KBr or RbCl-xBr multilayer structures exhibits a blueshift in affecting with two effects, namely an increase of the exciton kinetic due to quantum confinement and an increase of band gap in the well due to interface mixture formation. Whereas the confinement of exciton wave function is effectively occurred even in the well with width wider by ten times of exciton Bohr radius and seems to make the rise of exciton band steeper appreciably.The influence of the layer-layer interface mixture to the blueshift which is remarkable in the noannealed multilayer can be decreased by thermal annealing at appropriate temperature for layer by layer, and an interface mismatch free and interface mixture free structure is realized in annealed RbCl-KBr multilayer. The.interface mixture formation strongly depends on annealing temperature and evaporation, speed, and at the present, it is considered that the temperature 180ﾟ-200ﾟ C and the speed less than 1A^^ﾟ/sec are favorable.It is also revealed that, if.there is a large difference of lattice constant between the layer and the substrate crystal, the interface mismatch effect is important in the case of very thin film less than 100A^^ﾟ.The experimental chamber which is just constructed by the grant will be worked to research the conditions of the thermal annealing and the evaporation speed of thin layers in near future.