Research Of PbSe Quantum Dot-doped Glass Prepared By A Melting Method

Because of the quantum size effect of semiconductor quantum dots(QDs), the discrete energy levels of QDs becames sharpened, and fluorescence increased significantly comparing with the bulk materials, showing a series of wonderful optical, electrical and magnetic properties of QDs associated with the QD size. So that QD doped glasses became one of the focal researches in recent years. For example, PbSe QD has a strong quantum confinement effect and high quantum yield as high as(300~700)% due to the size of QD much smaller than that of the Bohr radius(46nm), aroused great attention in recent years.In this dissertation, PbSe QD-doped sodium-aluminum-borosilicate glass is firstly fabricated successfully by using a melting method of one-step heat treatment. Measurement on the PbSe-QD doped glass shows that there is PL emission locating in 1440 ~1695 nm. However, it shows deficiencies, such as low concentration of QD, weak PL-emission intensity, and poor controllability of QD size during the period of preparation.Then, such a PbSe QD doped glass is optimally prepared by using the melting method of two-step heat treatment. By this way, we obtain the QD size distributing within 3.63~4.33 nm and with the doped volume ratio of 2% in the glass. The optimal heat treatment temperature is determined by using a differential thermal analysis. The crystallization, particle size and distribution of the QDs in the glass are observed by a X-ray diffractometer and a transmission electron microscopy(TEM). The absorption and photoluminescence(PL) spectra of the QD are also measured by a UV-visible-NIR spectrophotometer and a fluorescence spectrometer, respectively. There is evidence to show that only when the first heat-treatment time is between 3~5 h and the temperature is 500 °C, the glass has PL emission, ranging in 1220~1279 nm and with FWHM of 200 nm. For the second heat treatment, the optimal time and temperature are 10 h and 540 °C, respectively. An empirical formula is given for the PbSe QD size depending on the first heat treatment time.The method of PbSe QD doped glass presented in this dissertation can help to form QD doped fiber devices with high gain in the future.