Highly ordered copper oxide (Cu2O) nanopillar arrays using template assisted electrodeposition technique and their temperature dependent electrical characteristics

Abstract

Highly ordered Copper Oxide (Cu2O) nanopillars were successfully grown inside the porous anodized alumina (AAO) template by electrodeposition technique. To liberate the AAO template to get the free standing nanopillars, several etching trials were conducted using sodium hydroxide (NaOH) solution of varying concentration (ranging from 1 M to 5 M) and reaction time (8–60 min). On investigating the etched samples using scanning electron microscope, it was found that the sample treated with 1 M NaOH for 60 min yielded AAO template free standing vertically aligned nanopillars. Resistances of these nanopillars were found to be three orders of magnitude greater than the thin film which was used as a control sample. The temperature dependent (180–300 K) current-voltage (I-V) measurement on nanopillars showed non-linear characteristics which was analyzed using back to back schottky diode model and thermionic field emission (TFE) theory. Our calculations revealed that the carrier transport is diffusive (mean free path = 8.9 nm < < length of nanopillars = 4 μm) in nature and the existence of defect sites with activation energies of 0.3 and 0.6 eV which acts as hole traps. This present work demonstrates a reliable technique for realizing vertically aligned Cu2O nanopillars which could find application in solar cell, gas sensors, Li ion batteries, and memory devices.