Optoelectronic properties in vertically aligned ZnO/Si-nanopillars
Yuan-Ming Chang1*, Hsin-Yi Lee2, Chih-Ming Lin3, Jenh-Yih Juang1
1Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
2Department of Materials Science, National Synchrotron Radiation Research Center, Hsinchu, Taiwan
3Department of Applied Science, National Hsinchu University of Education, Hsinchu, Taiwan
* presenting author:張原銘, email:ymchang7@gmail.com
An effective method of fabricating vertically aligned silicon nanopillars (Si-NPs) was realized by using the self-assembled silver (Ag) nanodots as natural metal-nanomask during dry etching process. The obtained Si-NPs were preferentially aligned along the c-axis direction. Ultrathin ZnO films (~9 nm) were subsequently deposited on the Si-NPs by atomic layer deposition (ALD) to enhance the field emission property. The average diameter of the ZnO/Si-NPs is in the order of tens of nanometers, which enables efficient field emission and gives rise to marked improvement in the field enhancement factor, β. The turn-on field defined by the 10 µA/cm2 current density criterion is ~ 0.74 V/µm with an estimated β ~ 1.33×104. The low turn-on field and marked enhancement in β were attributed to the small radius of curvature, high aspect ratio, and perhaps more importantly, proper density distribution of the ZnO/Si-NPs.

Keywords: ZnO, silicon nanopillars, filed emission, atomic layer deposition