X-ray excited optical luminescence of ZnS nanowires

Using x-ray excited optical luminescence (XEOL) we determined the local phase of the luminescing sites in ZnS nanowires. The inset shows the optical spectrum obtained after excitation with 1100 eV x-rays. There are three main peaks: a band-edge, exciton state at 338 nm, a defect-related emission at 430 nm, and a Au-related feature at 520 nm. (Au is used as a catalyst to grow the wire.) By monitoring the yields of each peak as a function of energy at the Zn L edge we are able to determine the crystollographic phase associated with each feature. The 338 nm peak is similar to the spectrum obtained using the x-ray fluorescence (XRF) yield and has a wurtzite signature while the 430 and 520 nm curves resemble sphalerite. These results show that the 338 nm exciton state originates in the dominant, wurtzite phase of the wire while the other two peaks occur in dilute (~0.1%) regions of sphalerite [R. Rosenberg, G. Shenoy (APS) T.K. Sham(Univ. W. Ont.)]

Local Contact: Richard Rosenberg ( rosenberg@aps.anl.gov)

Posted by: Becky Gagnon ( gagnon@aps.anl.gov)
Content by: Jonathan Lang ( lang@aps.anl.gov)