Study On Diagnosis And Film Characterization Of TiO₂ Plasma In Pulsed Laser Deposition Process

Pulsed laser deposition（PLD）can control the deposition process by changing laser parameters,adding background gas,adjusting the distance between target and substrate and the substrate temperature,and has been used as a potential technology in the preparation of various nano-thin film materials.The technology has high deposition rate and good compatibility,which is very suitable for the deposition of oxide films.However,the interaction between laser and solid sample target is a complex process,which consists of different stages:laser ablation target;Plasma generation;Laser and plasma interaction;The plasma expands and interacts with the substrate.These processes all play a very important role in film growth.Due to the excitation and ionization of plasma plumes produced by laser ablation,it is very important to diagnose the thermodynamic parameters of plasma such as electron number density and electron temperature during pulsed laser deposition.TiO₂ is widely used as a wide band gap semiconductor material.There have been a lot of studies on the preparation of TiO₂ thin films by pulsed laser deposition,mainly focusing on the effects of macroscopic experimental parameters on the properties of the films,but the characterization of ablative plumes during deposition using optical emission spectroscopy（OES）seems to be rare.In this paper,plasma state parameters in the deposition process were diagnosed by spectroscopic method,so as to analyze the influence of plasma state parameters on film properties,and provide reference for further precise regulation of pulsed laser deposition of TiO₂ films.（1）Based on the existing experiments,a set of experimental equipment for pulsed laser deposition is assembled.By optimizing the experimental design,TiO₂ thin film deposition experiments were carried out under different pulsed laser energies,and real-time monitoring of plasma emission spectra during deposition was carried out by spectroscopic method.TiO₂ films with different ablative energies were prepared by obtaining the spatio-temporal resolution spectral information of TiO₂ plasma.（2）The fitting information was extracted from the collected TiO₂ plasma spectra,and the intensity evolution results of particles with different charge states of the two elements were analyzed.Saha-Boltzmann method and Stark broadening method were used to perform diagnostic calculation on the spatio-temporal evolution trends of electron temperature and density under different laser energies.（3）Using field emission scanning electron microscopy（SEM）,X-ray energy spectroscopy（EDS）,Raman Spectrum,UV-vis absorption spectroscopy（UV）,and photoluminescence（PL）,The surface morphology,element distribution,molecular vibration mode and optical properties of the obtained TiO₂ thin films were characterized and analyzed,and the influence of plasma state on the properties of the deposited films under different laser energies was discussed.