Al <sub> 2 </ Sub> O <sub> 3 </ Sub> Thin Film Low Temperature Deposition And Al <sub> 2 </ Sub> O <sub> 3 </ Sub>-Si Interface Properties Of Chalcogenide Preparation And Characterization Of Glass Film

This thesis includes two parts.One is the preparation of aluminum oxide (Al₂O₃) thin films by using electron cyclotron resonance plasma assisted pulsed laser deposition(ECR-PLD).We discussed the basic properties of the films and also analyzed the characteristics of annealed samples,whose crystallic phases have been converted and optical characteristcs have changed.Besides,we found an interface layer appeared between the film and the substrate after heat treatment.The second part is the preparation of chalcogenide glass thin films on trasparent substrates by using the method of pulsed laser deposition(PLD).We studied the trasmittance property of prepared samples,and calculated several optical coefficients of the samples for the further study of nonlinear optical characteristcs.PLD is a recently developed technique which has been successfully used for the preparation of many kinds of thin films.Electron cyclotron resonance (ECR) microwave discharge can produce plasma with high density and high degree of ionization at low pressures.We developed a novel method for film synthesis named ECR-PLD by combining PLD with ECR microwave plasma. This method colligates the advantages of PLD and ECR plasma:as a strong non-equilibrium process,pulsed laser ablation would break through some limitations of equilibrium thermodynamic;particles generated from pulsed laser ablation have high kinetic energy and potential energy,which make it possible to synthesize thin films at low temperatures;ECR discharge could create large amounts of reactive species,which could react with ablated particles at high rates;concurrent bombardment of the growing film by low-energy ECR plasma steam would be beneficial to the growth of thin films.This technique is especially suitable for compound formation and film growth at low temperatures.In this thesis,we used this technique to prepare Al₂O₃ thin films.Al₂O₃ is a new kind ofⅢ-Ⅵsemiconductor material,which has excellent properties,such as high hardness,good wear resistance,high dielectric constant(four times more than that of SiO₂),good chemical inertness,high thermal conductivity.Al₂O₃ has emerged as one of the promising substitutes for the SiO₂ dielectric layer in complementary metal-oxide-semiconductor (CMOS) device fabrication.Atomic layer deposition(ALD),sol-gel,pulsed laser depostion(PLD) etc.are often used to prepare Al₂O₃ thin films.In this thesis,we presented our improvement on low-temperature preparation of Al₂O₃ films by means of PLD with assistance of oxygen plasma.We compared the characteristics of as-deposit and annealed samples, found that the phase changed as well as the optical properties.Heat treatment also caused the interface layer of SiO_x appeared between the film and the substrate.Under different film preparation and annealing conditions,we studied the reasons and factors for interface layer formation.Chalcogenide glasses contain one or more of the chalcogen elements (groupⅥelements S,Se,Te) as alloy elements.They behave as semiconductors,or more precisely,they exhibit amorphous semiconductor behaviour with band gap energies from 1 to 3 eV.Chalcogenide glasses exhibit excellent transmission in the near and far infrared spectral region.They are high refractive index materials with a nonlinear refractive index typically hundred times than that of silica,with a low maximum phonon energy. Furthermore,owing to their photo sensitivity,chalcogenide glasses allow preparation of writing channel waveguides.For the samples preparation, quenching is often used to produce buke materials.For film materials, evaporation,sputtering and chemical vapor deposition(CVD) are three main methods.We used PLD to synthesis chalcogenide glass films on transparent substrates,studied the transmittance property of the films and calculated optical coeffients based on it.Through synthesis of two kinds of thin films,we demonstrated the application of PLD and ECR-PLD on material preparation.We also studied the characteristcs of the prepared thin films and confirmed the their advantages for industry application.