Cathodoluminescence and photoluminescence of individual silicon nanowires

Photoluminescence (PL) spectroscopy and Cathodoluminescence (CL) spectroscopy and imaging have been utilized to resolve red and blue emission bands from silicon nanowires. We have found that the blue emission band comes from local defects in the silicon dioxide shell of the wires while the red band comes from interfaces between the silicon dioxide shell and the crystalline silicon core. Time-resolved PL spectroscopy of hydrogen- and oxygen-terminated silicon nanowires, indicates that surface chemistry plays an essential role in determining the luminescence properties of the nanowires. We suggest that the PL lifetime should be related to nonradiative relaxation processes that take place at the interface of the silicon core and the clad material of the nanowires.