Photoelectric Properties of Doped Perovskite Oxide Films and Evaporating Metal Nanocrystal Arrays on AAO

Author:Zhao Chen Wei

Supervisor:chen chang le


Degree Year:2018





Perovskite oxides,with their abundant physical,chemical properties,cheapprice,stable performance,easilychemical doping,has become an important class of photoelectric characteristics.Because of the complexity of the doped perovskite oxide filmand diversity,based on photoelectric perovskite oxide thin film preparation and properties of research still exist more insufficient,especially for different kinds of photoelectric properties of perovskite oxide thin films were also without further system research,the transport mechanism of the photovoltaic process also needs in-depth analysis and research.In this paper,a variety of droped perovskite oxide films/heterojunctions were prepared,and the electrical transport properties were analyzed and discussed.The main work of this paper includes the following aspects:(1)BiFeO3/La0.7Sr0.3MnO3 heterostructure was fabricated by pulsed laser ablation.The leakage current conduction was to be dominated by Poole-Frenkel mechanism in the BiFeO3/La0.7Sr0.3MnO3 heterostructure.Additionallly,we report photoconductivity in BiFeO3/La0.7Sr0.3MnO3 heterostructure under illumination from 160mW/cm2 and 200mW/cm2 green light source.(2)Partial substitution of group 10 metal for titanium is predicted theoretically to be one of the most effective waysto decrease the band gap of PbTiO3-based ferroelectric photovoltaic materials.It is therefore of interest toexperimentally investigate their ferroelectric and photovoltaic properties.In this work,we focus on the electricaland photocurrent properties of Ni-doped PbTiO3 thin films prepared via a sol-gel route.The nickelincorporation does not modify the crystalline structure of PbTiO3 thin film,but it can increase the dielectricconstant,ferroelectric polarization and photocurrent,and simultaneously decrease the band gap.The maximumremnant polarization(Pr)of 58.1μC/cm2 is observed in PbTi0.8Ni0.2O3 thin film,and its photocurrent density isimproved to be approximately one order larger than that of PbTiO3 thin film and simultaneously exhibits thepolarization-dependent switching characteristic.(3)Hydrogen was introduced into BaSnO3 through CaH2 reduction ofBaSnO3 thin films,and the electrical properties,as well as the photo-response behavior,wereinvestigated.Secondary ion mass spectroscopy demonstrated the uniform distribution of hydrogenwithin the BaSnO3 thin film.The addition of hydrogen greatly enhanced the conductivity of the BaSnO3thin film,exhibiting a carrier concentration8.04?1019 cm-3 and mobility9.52cm2V-1s-1 at 300 K,and thus resulted in a fast relaxation process in the transient photoconductivity,which was characterizedby a double exponential function indicating two physical contributions.(4)Mn doped ZnO(ZMO)thin film was deposited by magnetron sputtering on p-Si(100),X-ray diffraction(XRD)and atomic force microscopy(AFM)were utilized to characterizethe microstructure properties of film.The results show that the ZMO film was consisted of polycrystalline film and crack-free.The temperature dependent transport and photoresponse properties of ZMO/Si heterojunction were investigated.It was found that the heterojunctions shows excellent rectifying behavior.As the temperature decreases,the barrier height and the reverse saturation current decrease,while the ideality factor increases.Photocurrent is produced by illumination.Under reverse bias,photocurrent increases dramatically and reaches saturation at a certain critical voltage.The critical voltage increases as temperature increases.(5)By studying the effect of substrate temperature and deposition angle on nanostructures,an active control mechanism for nanoarray formation was revealed.The results indicate that the periodic array provided by the AAO substrate provides a nucleation density that exceeds the hole density,while a sufficiently high atomic mobility promotes grain aggregation.The AAO substrate provides an effective method for fabricating an anisotropic grain array structure,which will help deepen the deep understanding of the substrate nanotopography on the growth energetics and dynamics of the film,and prepare for the preparation of other The new nanostructured films provide theoretical basis and experimental basis.