Growth and characterization of Au nanoparticles embedded In2O3 composite films

- Au nanoparticles embedded In2O3 films showed surface plasmonic absorption.
- Observed zero valance of Au confirm elemental state of gold nanoparticles.
- Persistent photocurrent indicates the presence of deep trap levels.

Au nanoparticles embedded In2O3 thin films (In2O3:Au) were grown by DC reactive sputtering method in three different target configurations. Presence of Au in In2O3 matrix was confirmed by glancing angle X-ray diffraction (GXRD) and transmission electron microscopy (TEM). Crystallite sizes of Au were obtained by Debye-Scherrer formula from GXRD data. Localized surface plasmon resonance was observed for In2O3:Au samples from optical absorption measurement at peak value of ~ 550 nm and inferred red shift of resonance peak towards the increasing crystallite size. Rutherford backscattering spectrometry (RBS) studies of selected samples on Si substrate showed minor In diffusion and absence of Au diffusion into the Si substrate. X-ray photoelectron spectroscopy (XPS) studies revealed that the chemical state of Au is neutral. The samples with high Au content exhibited persistent photoconductivity due to the sub band gap absorption indicating the introduction of sub band gap trap levels in In2O3.