Synthesis of CdO and NiO-Based Sandwich Structures Using Pulsed Laser Deposition: Morphological and Optical Characteristics

Abstract

High-quality thin films of nickel oxide (NiO) and cadmium oxide (CdO) were deposited on porous silicon wafers and glass slides using pulsed laser deposition (PLD). Laser pulses at 1064 nm and 700 mJ were used at a low pressure of 10⁻³ Torr, followed by a 60 min annealing at 300 °C to stabilize the films. A porous silicon wafer was prepared using a (10 min) photochemical etching process, resulting in a surface with a favorable diffusion of the particle distribution. A scanning electron microscope (SEM) was used to analyze the distribution of CdO and NiO particles on the porous silicon surface at (200 pulses) and (300 pulses) for CdO and NiO, respectively. The results showed that increasing the pulse count improved the homogeneity and regularity of the particle distribution on the porous silicon surface, while simultaneously reducing the particle size. The etching process facilitated surface dispersion and the formation of a homogeneous nanolayer on the porous silicon films, as evidenced by the photoluminescence (PL) spectra of CdO and NiO. UV-Vis analysis revealed that CdO and NiO deposited on glass slides exhibit strong absorption at short wavelengths, with film thickness amplifying this absorption.