Electron irradiation effect and photoluminescence properties of ZnO-tetrapod nanostructures

The effect of high-energy (200 keV) electron irradiation on ZnO-tetrapod (ZnO-T) nanostructure has been investigated by employing in situ scanning tunneling microscopy (STM) holder inside TEM. The microscopic results have revealed that the product consists of highly single-crystalline ZnO-T structures. The photoluminescence spectra show the increased amount of defects which lead to shift in the emission peak position in ultraviolet (UV) region and enhance the PL performance in visible luminescence (VL) region of ZnO-T nanocrystals. The in situ measurements show asymmetric Schottky contacts at the both ends interfaces under electron irradiation. The current-voltage (I-V) characteristics have revealed that the increase in electron density (range of ∼0-25 pA cm^-2) leads to an increase in the current along with the increase in carrier concentration from 1.1 × 10¹⁷ cm^-3 to 3.2 × 10¹⁷ cm^-3. In addition, it has been interestingly found that at high bias voltage, Schottky contacts turn to Ohmic contacts at the both ends with the influence of irradiation-matter interaction. The results strongly suggest that the ZnO-T is considered as a promising candidate for applications in irradiation environments.