"Electrical and Optical Properties of Nanocrystalline-Si-Dispersed Film with Periodical Modulation of Its Layer Structure"

纳米硅分散薄膜是由纳米硅分散组成的氧化硅薄膜，是一种新型发光材料，具有高效的可见光致发光性能。然而，纳米硅分散薄膜的导电性普遍较低，因此很难通过电流注入来实现发光。在本项目中，我们的目标是通过形成具有高效发光层和低阻富硅层的周期性多层膜来同时实现高效发光和高电导，通过改变氧气流量来调节薄膜的氧含量来实现多层结构的形成。结果是，由于形成的纳米硅的尺寸取决于薄膜的成分，所以在高温热退火后，纳米硅的平均尺寸大约是空间周期性的调制。证实了多层结构导致的电导率增加，但多层结构的影响仅在周期小于100 nm的多层膜中观察到。这与光致发光峰值波长为800 nm的分布布拉格反射器的周期~300 nm不相容。这种不兼容性必须在未来得到解决。

Nanocrystalline (nc-) Si-dispersed films, which are the silicon oxide thin films including nc-Si dispersively, are a new light-emitting material providing high efficiency visible photolminescence. However, the nc-Si-dispersed films generally have low electrical conductivity, and thus there are difficulties in achievement of light emission by current injection. In this project, we aimed to achieve both high efficiency light emission and high conductivity simultaneously by the formation of periodical multilayers with high-efficiency light-emitting layers and low-resistivity Si-rich layers.The formation of the multilayer structure was realized by modulating oxygen content of the films through a variation of O_2 flow rate. As a result, a spacially periodical modulation of the average size of nc-Si was bought about after high-temperature thermal annealing because the size of nc-Si formed depends on the composition of the films. An increase of the conductivity due to the multilayer structure was confirmed but the effect of multilayer structure observed only for the multilayer that has a period less than 100nm. That was not compatible to the period 〜300 nm of distributed Bragg reflector for 800-nm wavelength region, which is the peak wavelength of photoluminescence. This incompatibility must be solves in future.