Investigation On The Preparation And Properties Of BaM Films On Si Substrate By PLD Method

With the development of modern communication technology,microwave ferrite devices play an increasingly important role as the core components of communication systems.Magnetoplumbite ferrite material,because of its high magnetocrystalline anisotropy constant,high saturation magnetization,high coercivity and other characteristics,is attracted more and more people's attention.M-type barium ferrite Ba Fe12O19(Ba M),as a magnetoplumbite ferrite,has a high cost and is widely used in microwave devices.At present,miniaturization,chip formation and integration are the urgent directions for the development of magnetic devices.It is an inevitable trend that materials are applied to various devices in the form of thin films.Therefore,how to prepare high-quality Ba M thin films that meet the requirements of microwave devices is worth further studying.As a core semiconductor material,Si has a large proportion of semiconductor components and circuits.It is of great significance to study the integration of circuit on Si substrate.This paper is devoted to the preparation of high quality Ba M film on Si substrates by pulsed laser deposition(PLD).However,the Ba M film prepared by PLD needs to be crystallized at high temperature.At this time,Si is easily diffused into the Ba M film,which affects the performance of the Ba M film.Therefore,the effects of PLD preparation(oxygen pressure,annealing)and buffer layer on the properties of Ba M film were investigated.Firstly,the Ba M bulk is prepared by a two-step sintering method.The effects of the first sintering temperature T1,the second sintering temperature T2 and the holding time t on the microstructure and properties of Ba M were investigated.The study found that the two-step sintering method can effectively inhibit grain boundary migration while maintaining grain boundary diffusion.Under the condition of T1 = 1325 oC,T2 = 1300 oC and holding time of 20 h,the internal grain size of the prepared Ba M bulk is small and uniform,the compactness is the best,the grain size is 2.92?m,the saturation magnetization is up to 69.26emu/g.Secondly,Ba M films are prepared on Si(100)substrates by using pulsed laser deposition equipment with Ba M bulk as the target.First,the uniformity of the film was investigated.The study found that the film in the center of the circle,a radius of 3.2±0.4mm circular area relatively uniform,the film thickness error of ±30nm.Second,the effects of oxygen pressure parameters and annealing temperature on the microstructure and properties of Ba M film were investigated.The Ba M film prepared with oxygen pressure of 1Pa and 3h at 900 oC has better micromorphology and magnetic properties,and their saturation magnetization reaches 295emu/cm3.Finally,the performance of the film is regulated by increasing the buffer layer,and the high quality Ba M film is prepared.The effects of YSZ and Au buffer layers on the structure and properties of Ba M films were investigated.The YSZ buffer layer can effectively prevent the diffusion between the Si substrate and the Ba M thin film.The prepared Ba M thin film has a small coercive force and a small microwave loss at a high frequency.The Au thin film and Ba M thin film prepared by depositing and annealing at low temperature has better C-axis orientation,the maximum saturation magnetization reached 326emu/cm3.