Research On Low Loss Microwave Monocrystal Thick Films And Their Application In Planar High Q Factor Resonators

With the development of science and technology,the various performance requirement of military and civil electronic equipment is increasing which drew higher demand in the performance of microwave gyromagnetic device.This puts forward higher requirements on the performance of microwave gyromagnetic materials.At the same time,the characteristics of miniaturization,planarization,and integration of modern microwave circuits have also made the research of thin film materials flourish.The yttrium iron garnet(YIG)is a kind of widely used microwave gyromagnetic material.The resonator designed based on it is a key part of the test equipment such as vector network analyzer.Most of the traditional YIG resonators use small balls as resonators,but they are bulky,complex in design,and are not compatible with modern microwave integrated circuits.In this paper,a low-loss microwave YIG thick film is developed.Based on this material,a thin film resonator is designed to make up for the shortcomings of the small-ball resonator.The device is small in size,simple in structure,and the planarized structure is easily integrated with MMIC to confirm with the requirements of modern communication systems for devices.In this dissertation,single crystal La:YIG film was prepared by liquid phase epitaxy,and a planar high-Q YIG-tuned resonator based on the magnetostatic surface wave(MSSW)was designed.Firstly,La:YIG thick films were prepared by LPE,the growth conditions of La:YIG thick films and the performance of La:YIG thick film are explored.The saturation magnetization of La:YIG thick film prepared by LPE was 1700 Oe,the ferromagnetic resonance line width can reach 1.05Oe@3GHz and the thickness of film can reach 83.11?m.Secondly,the etching process of YIG thin film is studied.The etching process of YIG thin film is of great significance to the design of the magnetostatic wave device and the study of spintronics.The effects of etching concentration,temperature,time and other parameters on etching results were explored,finally,a method of 4-layer mask was applied to improve the etching effect significantly.Finally,a kind of x-band magnetostatic surface wave resonator was designed based on the La:YIG film prepared in the experiment,tests found that in the range of frequency tuning,load Q factor up to 2750,but the insertion loss is more than 15 db.After making some periodic grooves on the film by etching,the load Q factor up to 2826,the insertion loss reduced to less than 15 dB.