Studies Of Reasonance Absorption Of Ag Nanoparticles Films And Enhancement Photoelectric Properties Of ZnO/Ag Composite Films

Noble metal nanoparticles(NPs)can be able to strongly interact with light and produce localized surface plasmons resonance effect(LSPR)with absorbing certain wavelength.The NPs resonance absorption is related to metal properties,particle size,shape,particle spacing and the surrounding environment,and so on.The metal Ag possesses the strongest LSPR effect due to smaller imaginary part of dielectric constant.The Ag NPs resonance absorption can tune to visible light area that can increase the utilization of the solar spectrum by regulating these parameters.So the study is very necessary of influence NPs morphology on resonance absorption.The photoexcited electrons of noble metal NPs can be injected into the semiconductor conduction band by light irradiation and the local electromagnetic field can also be enhanced.Besides,NPs can be used as optical antenna to focus light energy around the NPs,which is critical for the effective capture solar energy.These unique properties are particularly advantageous for hydrogen production by water splitting,photocatalysis,photoelectric detector and photovoltaic devices.Among all semiconductors,ZnO has been most widely attention due low price,stable physical and chemical properties.Nevertheless,its large band gap requires high energy photons,which lie in ultraviolet light area and constitute a small percentage of sun light.Besides the photoexcited electronic-hole pairs can rapidly recombination,its seriously affected enhancement of the photoelectric property.The noble metal NPs modified ZnO can be used to enhance photoelectric conversion efficiency.The plamon-induced hot electron can be injected into the ZnO conduction band to improve the carrier concentration.At the same time,it can promote the electronic-hole pairs separation.And it is also enhance absorption in the visible light to improve the utilization of solar energy.So it can improve the photoelectric properties by reasonably designing and preparing ZnO/Ag nanostructures.The main research content can be divided into two aspects in the work,as follows:(1)We studied the influence different thicknesses and substrate temperatures(roomtemperature=RT,100? and 200?)on LSPR of Ag NPs films grown by Laser Molecule Beam Epitaxy(LMBE).The results show that with the thickness increases the LSPR band broaden and wavelength red-shift at same temperature.The intensity of Ag NPs resonance absorption is also increase.When form a continuous film,there is no obvious absorption peak.And with the increases of the substrate temperatures the LSPR band displays sharp,blue-shift and significantly symmetric at same thickness.The LSPR wavelength can be largely tuned in the visible light range of 470 nm to 770 nm when the thickness of Ag NPs increases from 3 nm to 17 nm at RT.(2)We studied the influence different structures on optical and photoelectric properties of ZnO/Ag nanostructure films grown by LMBE.The total ZnO thickness is 150 nm,and embedded Ag NPs film layers(each Ag layer thickness as 5 nm)are different in this ZnO/Ag nanostructure films.The results show that the ZnO/Ag nanostructure films have more much photocurrent than the pure ZnO films under light irradiation.With embedded Ag NPs film layers increases,the optical and photocurrent properties are both increase.Besides,the photocurrent is further improved in antenna-on ZnO/Ag nanostructure films.When embedded Ag NPs layers continue increase,each layer of ZnO film will become thin that lead to loose structure,the photoelectric property is not stable.So under comprehensive assessment,we choose sample antenna-on ZnO/Ag 3D nanostructure films as a good example in this work.