Investigation of the Influence of Laser Parameters on the Thickness and Surfaces Roughness of TiO2 Thin Films Fabricated using Pulsed Laser Deposition

Abstract

Among the available thin film deposition techniques, pulsed laser deposition (PLD) is an effective technique to deposit high-quality thin films of various multicomponent materials which based on laser ablation, where high-power laser pulses are applied to stoichiometrically transfer material from a target surface onto a substrate. which provides a well adherent thin film with good mechanical rigidity. In this thesis Titanium Dioxide thin films with a thickness range of a few tens of nanometers to few hundreds nanometers were successfully deposited on different glass substrates at room temperature and atmospheric pressure using pulsed laser deposition technique. Titanium dioxide powder, in the Anatase form, was compressed to form solid disks as a target material and irradiated with frequency doubled Q-switch Nd: YAG laser (532 nm) to deposit two groups of thin films on different substrates. first based on varying number of laser pulses (5, 10 and 15 pulses) while keeping all other parameters remains constant, the same pulse energy (150 mJ) and same Repetition rate (10 Hz). In the second part based on varying the laser pulse energy (100, 150 and 200 mJ) while keeping the other parameters remains constant, number of laser pulses (10 pulses) and the same laser repetition rate (10 Hz). In the both experiments an atomic force microscopy (AFM) was used for the characterization of the thickness and topography of these thin films. The results showed that the thickness of the films was in the range of tens nanometers and it is increased exponentially with the number of laser pulses and the laser pulse energy. The dependence of average roughness (Ra) and the root means squire roughness (RMS) on number of laser pulses and laser pulse energy also were investigated and the results showed that the (RMS) increase exponentially with the number of laser pulses and the laser pulse energy to specific value, and then decrease exponentially that the whole curve looks like Gaussian shape. the influence of the relevant parameters on the thin film thickness and roughness were plotted IV that in present researches could be used to obtain good quality thin films with specific thickness needed for specific applications.