Polarity-Dependent High Electrical Conductivity of ZnO Nanorods and Its Relation to Hydrogen

Abstract

A statistical analysis of the electrical properties of selective area grown O- and Zn-polar ZnO nanorods by chemical bath deposition is performed by four-point probe resistivity measurements in patterned metal contact and multiprobe scanning tunneling microscopy configurations. We show that ZnO nanorods with either polarity exhibit a bulklike electrical conduction in their core and are highly conductive. O-polar ZnO nanorods with a smaller mean electrical conductivity have a nonmetallic or metallic electrical conduction, depending on the nano-object considered, while the vast majority of Zn-polar ZnO nanorods with a larger mean electrical conductivity present a metallic electrical conduction. We reveal, from Raman scattering and spatially resolved 5 K cathodoluminescence measurements, that the resulting high carrier density of ZnO nanorods with O or Zn polarity is due to the massive incorporation of hydrogen in the form of interstitial hydrogen in bond-centered sites (HBC), substitutional hydrogen on the ...