Study on Enhancement of Non-Phonon Excitonic Luminescence by using Inhomogeneous strain fields

在本工作中，我们研究了在硅衬底上生长的锗岛的生长特性和光学性质。对于Ge岛的生长，最重要的问题是Ge岛密度的增加和Ge岛尺寸的有序化。在这些问题上，我们尝试了两种方法。首先，我们利用了具有薄Si间隔层的堆叠Ge岛层，这导致。每个Ge岛层的相关性导致Ge岛尺寸的有序化。其次，我们利用了较低温度生长的Ge岛层，其上通过薄Si间隔层堆叠较高温度生长的Ge岛层，即使在高生长温度下也导致Ge岛的尺寸急剧减小。2001年，我们研究了SiGe/Si分布式布拉格反射镜（DBR）对SiGe量子结构发光的增强作用，并成功制备了反射率超过90%的DBR。我们还利用SiGe/Si DBR制作了微腔，通过该微腔对SiGe/Si量子威尔斯和Ge岛的发光进行了大幅调制。微腔效应也改善了发光的方向性。

In this work, we have investigated on the growth characteristics and the optical properties of the Ge islands grown on Si substrates. For the Ge-island growth, the most significant issues are increasing of the density of Ge islands and ordering of the size of the Ge islands. On these issues, we have tried two approaches. First, we have utilized staked Ge islands layers with thin Si spacer layers, which leads to. correlation of the each Ge islands layer resulting in the ordering of the size of the Ge islands. Second, we have utilize a lower-temperature grown Ge islands layers, on which higher-temperature grown Ge island layers are stacked via thin Si spacer layers, resulting in drastic size reduction of the Ge islands even at high growth temperature. In 2001, we have investigated on SiGe/Si distributed Bragg mirrors (DBRs) to enhance luminescence of SiGe quantum structures and successfully fabricated DBRs with a record reflectivity (>90 %). We have also fabricated a microcavity by using SiGe/Si DBRs, by which luminescence from SiGe/Si quantum wells and Ge islands drastically modulated. The directionality of the luminescence is also improved by the effect of microcavity.