UV-photon and electrically driven resistance switching in ZnO nanotube arrays

TL;DR

This study demonstrates that ZnO nanotube arrays exhibit persistent photoconductivity driven by UV photons and conductance switching via electrical stimuli, with defect states playing a key role in these phenomena.

Contribution

The paper reveals the dual photonic and electrical switching behaviors in ZnO nanotubes and links these effects to defect localized states, providing new insights into their optoelectronic properties.

Findings

ZnO nanotube arrays show persistent photoconductivity.

Electrical switching exhibits a gradual decay from high to low conductance.

Defect localized states at ~240 meV are involved in the phenomena.

Abstract

Vertically aligned ZnO nanotube arrays fabricated on an ITO substrate are found to exhibit strong persistent photoconductivity (PPC) effect and electrically driven conductance switching behavior, though the latter shows a gradual decay from high conductance state to a low conductance state. Unlike the electrical switching, the PPC cannot be reset or reversed by an electrical pulse. Excitation wavelength dependent conductance measurement indicates the presence of the defect localized states (DLS) ~ 240meV above the valence band edge, in support of the hypothesis that the doubly ionization of these DLS are responsible for the PPC effect.