Investigation of hydrothermally-produced ZnO nanorods and the mechanisms of Li incorporation as a possible dopant

Abstract

Zinc oxide (ZnO) has emerged as one of the most promising candidates for mass-producing cost-efficient optoelectronic devices. This is primarily because it can be synthesized in high-quality nanostructures on a wide range of substrates through relatively simple chemical methods. However, producing p-type ZnO, regardless of the chosen method, remains an open and controversial issue. In this work, Li-doped ZnO nanostructures of varying Li-cocnentration were produced via a two-step hydrothermal growth synthesis and an in-depth analysis based on with Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffraction (XRD), Raman Spectroscopy, Extended X-Ray Absorption Fine Structure (EXAFS) Spectroscopy, and temperature-dependent Photoluminescence (PL) was carried out in an effort to gain insights into the Li-incorporation mechanisms. The findings indicated a strong interplay between the native defects responsible for the inherent n-type character of the material and Li incorporation. It is suggested that this interplay hinders the successful conversion of the Li-doped nanorods into p-type nanostructures and that when employing the hydrothermal approach it is essential to identify the precise conditions necessary for genuine Li incorporation as a Zn substitutional.

Keywords

• ZnO nanorods
• Li-doping
• Hydrothermal growth
• Point defects
• EXAFS
• XRD