Research Of QDs’ Fluorescence Enhancement Effect Based On Porous Silicon Photonic Device

Porous silicon(PSi) is a material which has many remarkable properties, not only large internal surface areas it has, but also it can be fabricated various types photonic devices. Combining PSi photonic devices with other materials has been investigated by many researchers in recent years, utilizing these combinations can improve the properties of materials, it can also fabricate sensors with more brilliant performance.In thesis, we utilized the special character of PSi and quantum dots(QDs), and attempted to research the fluorescence of QDS after combination. The work we did and results we obtained in this thesis are as following:We investigated the etching condition of PSi Bragg mirror whose high reflection band locates at 600 nm, which was etched by two different types silicon. In addition, we also researched the basic factors which affect thermal oxidation and H2O2 oxidation of PSi.By incubating functionalized silicon wafer and two different single layer PSi samples which have the same thickness and different pore size in CdSe/ZnS QDs anhydrous hexane solution for a period, CdSe/ZnS QDs can couple with samples successfully. After comparing the fluorescence intensity among silicon wafer and two different single layer PSi samples, the experimental results verified the fact that PSi has large internal surface areas, at the same time, we also found larger pore size could facilitate more QDs coupled with PSi surface, which indicated pore size of PSi had a significant effect on QD’s coupling with PSi.To research the relationship between QD’s fluorescence intensity and the structure of PSi Bragg mirror, we designed and fabricated a special PSi photonic device, which only permits QDs infiltrating into the first part of device. Experimental results show that the fluorescence intensity of QDs which infiltrated into the first part of PSi device can be enhanced when fluorescence peak falls into the high reflection band of PSi. In contrast, no significant enhancements happened when high reflection band of PSi device was far beyond fluorescence emission spectra of QDs, and the fluorescence intensity of these samples was approximately the same as the single layer samples. What is more, we also investigated the effect of Bragg mirror ’s periods on the QDs’ fluorescence intensity, results indicate that the reflectance of PSi device’s high reflection band had an apparent increment when Bragg mirror’ periods increased, of course, the enhancement effect of QDs’ fluorescent intensity was more apparent at the same time.