Spatially resolved photoluminescence study of single ZnO tetrapods.

ZnO tetrapods and nanowires were fabricated by a simple method of thermal evaporation of pure Zn powder in the air. These nanostructures, formed in different temperature regions of the same apparatus, displayed distinct photoluminescence (PL) characteristics. Spatially resolved PL measurements on legs of individual tetrapods show that the green luminescence (GL) decreases with decreasing leg diameter, and there was no detectable GL from nanowires grown simultaneously. These PL properties suggest that the green luminescence may not come from surface states, but rather from bulk defects.