Structural and optical properties of glancing angle deposited TiO2 nanowires array

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Titanium dioxide (TiO2) is a versatile semiconductor with applications in catalysis, energy, and electronics.
• Controlling the morphology of TiO2, such as synthesizing nanowires (NWs), can significantly influence its properties.
• Understanding the impact of synthesis methods and post-treatment on TiO2 NWs is crucial for optimizing their performance.

Purpose of the Study:

• To synthesize TiO2 nanowires (NWs) using glancing angle deposition.
• To investigate the structural, optical, and defect properties of TiO2 NWs compared to thin films (TF).
• To analyze the effect of high-temperature annealing on oxygen vacancies and optical characteristics.

Main Methods:

• Glancing angle deposition (GAD) with e-beam evaporation for TiO2 NW synthesis.
• Field emission-scanning electron microscopy (FE-SEM) and Transmission electron microscopy (TEM) for morphological analysis.
• X-ray diffraction (XRD), Photoluminescence (PL) spectroscopy, and optical absorption measurements for structural and optical characterization.

Main Results:

• TiO2 NWs with an average length of 490 nm and diameter of 80 nm were successfully synthesized.
• TEM confirmed wide dispersion of NWs at the top surface.
• A 0.03 eV blue shift in PL emission was observed for NWs compared to TF, attributed to quantum confinement or surface effects.
• High-temperature annealing at 980°C partially reduced oxygen vacancies, confirmed by PL and optical absorption.

Conclusions:

• Glancing angle deposition is an effective method for producing TiO2 nanowires.
• The morphology and annealing process significantly impact the optical properties and defect concentrations in TiO2 nanostructures.
• The observed blue shift and reduction in oxygen vacancies suggest potential for tailored optical applications of TiO2 NWs.