Ellipsometry Study On Metal Oxide Nanometer Films

Since the 21st century,microelectronics,optoelectronics,solar cells and other electronic products based on metal oxides have penetrated into every aspect of people's daily life.Among them,wide band gap semiconductor oxides and phase-change metal oxides are the hotspot materials.These oxide materials are expected to be used as electrode layer,transparent window and dielectric layer in uncooled infrared focal plane array,information memory,light-emitting diode,spin quantum control,photovoltaic devices and electrochromic devices.In order to develop the potential applications of these materials,it is necessary to study the optical and electrical properties of these metal oxide materialsAt present,the researches on metal oxides are mainly focused on their preparation process,magnetic properties,electrical properties and optical properties The main research of electrical and magnetic properties is the research of current,voltage characteristics and hysteresis loop of the film.The study of optical properties mainly lies in the study of photoluminescence,absorption properties,optical constants,band gap width and phase transition of these materials.However,it can be expected that the optical properties of metal oxide film materials will be significantly different from that of bulk materials.This is because when the thickness of the material is reduced to a certain extent,the microstructure of the oxide film will change,resulting in changes in the physical properties of the film(such as electrical and optical properties).Many optical and electrical properties of thin film materials are related to grain and intergranular boundaries.Low dimensional nanoscale samples have smaller characteristic sizes.Among them,nano scale single crystal materials have fewer defects and impurities,so it is easier to observe the intrinsic properties of materials.In addition,low dimensional nano film materials have larger surface product.From the perspective of application,it is of great significance to study the optical properties of metal oxide nano filmsIn this paper,the optical properties of metal oxide nano films are studied based on spectroellipsometry and thin film preparation technology.The optical properties of vanadium dioxide film on different glass substrate are studied,and the phase transition properties of vanadium dioxide film under variable temperature conditions are studied;the optical properties of titanium dioxide film on different substrates are studied,and the differences of optical properties caused by substrate effect are explored;the differences of optical properties of zinc oxide film with different polarity are explored,and the differences of optical properties of zinc oxide film with different polarity are compared and analyzed The intrinsic mechanism of optical transition in homogeneous ZnO films.The main contents and research results of this paper mainly include the following aspects1.High quality vanadium dioxide nano films were prepared on different glass substrates by magnetron sputtering.The structure,composition,morphology and optical properties of the films were characterized and analyzed systematically.The influence of metal ion penetration in the glass substrate on the optical properties of the two vanadium oxide films was studied,and the internal mechanism of the ion penetration was preliminarily explored.The temperature changing conditions were also studied It is found that the blue shift of refractive index with temperature is not consistent before and after the phase transition temperature,which may provide a new way to study the phase transition properties of materials in the future2.High quality titanium dioxide nano films were prepared by magnetron sputtering on different substrates.The properties of the films,such as crystal phase,morphology,optical constant and optical transition,were investigated.The effects of lattice mismatch and ion permeation on the crystal and optical transition of the films were investigated.It was found that the crystal sizes of titanium dioxide films on different substrates were different,Furthermore,because of the quantum confinement effect,the optical band gap is affected.At the same time,the ellipsoidal spectrum and absorption spectrum are used to explore the band gap and optical transition of titanium dioxide.It is found that the optical band gap obtained by the ellipsoidal spectrum and absorption spectrum is consistent,and the film has high transmittance,which is expected to be used in industrial development3.The ZnO films with different polarities(o-polar,Zn polar)were prepared on sapphire substrate by molecular beam epitaxy.The structure,morphology,dielectric constant and light emission spectrum of the films were studied.AFM analysis showed that the surface of the Zn polarized films was rougher than that of the oxygen polarized films,and the reason was explored.The oxygen with different polarities was compared and analyzed the optical properties of zinc oxide and its optical band gap are studied.It is found that the optical band gap of Zn polar film has a red shift compared with that of O polar film,which may be caused by the impurity energy band at the bottom of the film conduction band.