Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Physics

Supervisor

Prof. Giovanni Fanchini

Abstract

Transparent conducting oxides (TCOs) are extensively investigated because of their applications as transparent electrodes in solar cells and light-emitting devices. TCOs of interest include indium-tin oxide, aluminum-doped zinc oxide, nickel oxide (NiO), and their combinations. There is strong interest in NiO because no heteroatoms are required to “dope” it at high transparency levels. It has been speculated that paramagnetic defects due to Ni3+ centers and O interstitials are responsible for the electrical conductivity of otherwise insulating and antiferromagnetic NiO, but direct investigation of such defects has been limited. Here, the electrical conductivity in nanostructured NiO thin films is investigated and correlated to the paramagnetic defect density extracted from electron spin resonance (ESR). Two types of ESR-active centers are identified and assigned, respectively, to localized paramagnetic defects and surface electronic states. Our work points at defect engineering as a necessary step to optimize NiO thin films for their applications as TCOs.

Download

Share

COinS