Study of Two Dimensional Electron System of Solids and Phase Transition.Due to High Density Excitation

我们开始进行这个项目是为了阐明电子激发态的二维性质和高密度激发下的相变。首先，在KCl衬底上制备了一层非常薄的PbI_2层，发现激子的平移运动是尺寸量子化的，激子的自陷在很薄的层中变得稳定。其次，通过对染料与半导体界面发光的分析可知，染料的激发电子转移到了半导体的导带中。第三，采用ICB法制备了CdTe薄膜，并发现随着电子束电流的增大，在CaF_2衬底上生长出了更好的晶体。第四，在镶嵌在氯化钠晶体中的CuCl超细粒子中，激子被量子化。特别是在高密度激发下，在这种微晶中形成了具有大结合能的激子分子。

We started to perform this project in order to clarify two dimensional properties of the electronic excited states and the phase transition under high density excitation. At first, a very thin PbI_2 layer was made on the KCl substrate and it has been found that the translational motion of the exciton is size quantized and the self-trapped exciton becomes stable in the very thin layer. Secondly, from analysis of the luminescence at the interface between the dye and the semiconductor, it is known that the excited electron of the dye is transferred into the conduction band of the semiconductor. Thirdly, the CdTe film is made by ICB method and the better crystal has been found to be grown on the CaF_2 substrate with increasing the electron beam current. Fourthly, in the very fine particle of the CuCl crystal embedded in a NaCl crystal, the exciton has been found to be quantized. Especially, the excitonic molecule with the large binding energy is formed in such a microcrystal under the high density excitation.