Improving carrier mobility with vanadium doping of transparent conducting CdO

Abstract

Cadmium oxide (CdO) is a transparent conducting oxide (TCO) with versatile applications, many of which are linked to its transparency in the Vis/NIR spectral range in addition to its unique electrical conductivity. Its optoelectronic properties can be controlled in order to bring them into a desired choice by doping method. Usually resistivity of TCO could be reduced by increasing Nel, which, in turns, reduces the transparency (especially in the NIR region) of TCO. Therefore, it is important to seek ways to reduce ρ by increasing of μel (rather than Nel) that also reduces the absorption.In the present work, CdO thin films doped with different amounts of vanadium (V) ions were deposited on glass and silicon wafer substrates by physical vapour deposition method. The films were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), optical absorption spectroscopy, and dc-electrical measurements. The obtained results show significant improvements in the conductivity (σ), mobility (μ), and carrier concentration (Nel) of host CdO. The measured utmost enhancement in conductivity by 420%, mobility by 766%, and carrier concentration by 201% for CdO films doped with 4–5wt% V. This suggests the possibility of using V-doped CdO films in different TCO applications.