Controllable Growth And Characteristic Of Phosphorus-doped ZnO Quantum Dots By MOCVD

ZnO,with a wide direct band gap of 3.37 eV at room temperature and a large exciton binding energy of 60 meV,is a promising candidate for electrical and optoelectronic devices.As a new nanostructure material,ZnO quantum dots(QDs)are attracting considerable attention for the ultimate quantum confinement can be established in QDs.It has gained more and more attention in optoelectronic devices such as laser diodes,single electron transistor.Thus,the research on the ZnO quantum dots is very important.Its fascinating applications depend on several factors,namely the particle size,size dispersivity and the density.So the controlled size,size dispersivity and density of ZnO quantum dots are the key issues of the future development.In addition,doping is fundamental to controlling the electrical properties of ZnO.So the research on the phosphorus-doped ZnO quantum dots is of importance for the application of ZnO quantum in the future.In this thesis,based on a comprehensive review of the research history and current status of ZnO quantum dots preparation and relative theory of quantum,we conducted a detailed study of ZnO and phosphorus-doped ZnO QDs grown on Si(100)substrates by MOCVD and its properties.We also analyze the behavior of the phosphorus in ZnO QDs.So far,a few of work has been reported on doping in ZnO QDs and there is no report on fabrication of phosphorus-doped ZnO QDs by MOCVD.The main content of this thesis is listed as follow:1.High quality self-assemble ZnO quantum dots(QDs)have been successfully grown on the Si(100)substrates by metalorganic chemical vapor deposition(MOCVD). TEM shows that each ZnO quantum dot with good atom array is single crystal. Room-temperature photoluminescence spectra reveal that the ZnO QDs exhibit a 3.7 nm blue shift because of the quantum confinement effect.2.The size,size dispersivity and density of ZnO quantum dots grown by MOCVD are analyzed with different condition.The density and size of ZnO QDs are controlled by growth time at the substrate temperature of 460℃.3.PL test shows that ZnO QDs with smaller size has larger bule shift,revealing the quantum size effect.4.Phosphorus-doped ZnO QDs were grown on n-type Si(100)substrates by MOCVD. High purity P₂O₅ powders were used as the phosphorus doping source which was evaporated by a special thermal evaporator.5.The phosphorus was introduced into ZnO QDs identified by XPS and EDS.The Fermi level of the QDs can be tuned by P doping,as provided by the VB XPS, which confirms the phosphorus is acceptor and electrical property is tailored in the ZnO QDs.