【作者】 杨青慧；

【导师】 张怀武；

【作者基本信息】 电子科技大学 ， 电子材料与元器件， 2009， 博士

【摘要】 当射频、微波、太赫兹(THz)波和光波段集成系统各自逐渐形成后，一个新的科学构想随之诞生，那就是能不能研究一种薄膜可同时应用于微波、THz和光波段，实现全频段大集成系统!本博士论文的整个研究工作正是对这一构想的探索和验证。首先，基于石榴石薄膜在小型微波器件和磁光集成器件应用中的低损耗特性，以及在THz波导中潜在的实用价值，我们设计优化出三个频段具有优异特性的掺杂石榴石薄膜系列；其次，我们提出新型无铅液相外延工艺，结合磁控溅射工艺，研制出几种不同成分的石榴石薄膜材料，分析了其在微波段、THz波段和光波段的性能，从理论和实验上探讨了其在全波段器件中的应用；最后，分别研究了薄膜在微波段、THz波段和光波段器件中的应用，结果表明这些石榴石薄膜在这三个波段内都有可选择的优异性能，这对未来的大集成系统具有重要的研究意义。论文秉承了上述基本思想，在基础理论、材料工艺和器件设计方面上都作了探索性和创新性研究，主要亮点工作与涉及的内容为：(1)“缓冲法”Bi：LuIG单晶体无铅液相外延薄膜研究：研究了大面积液相外延薄膜的微结构、表面形貌及缺陷的控制技术；提出了适用于无铅工艺的“缓冲法”技术，着重研究了GGG基片晶轴取向偏差以及薄膜外延速率对材料缺陷和均匀性的影响，通过工艺优化，获得了晶格失配小于0．08％、具有镜面平整性、兼具大磁光效应和小铁磁共振线宽的优质单晶LuBiIG薄膜。薄膜的饱和磁化强度4πMs=1562 Gs，磁光法拉第效应1．6～2．0度／μm(10倍于目前其他工艺得到的薄膜)，最小铁磁共振线宽2ΔH=2．8 Oe。(2)微波烧结旋磁铁氧体工艺研究：探索了微波烧结法在石榴石材料合成工艺中的应用，通过优化烧结曲线和烧结温度得到了性能优良的石榴石铁氧体材料。除了高效和节时外，微波法烧结石榴石铁氧体材料在烧结密度、介电损耗、介电常数和磁电损耗方面都较常规烧结方法具有优势；进一步拓宽微波炉的烧结均匀区可实现大尺寸铁氧体材料的制备，该方法不仅有助于提高小型化微波器件中应用的石榴石铁氧体基片性能，而且在溅射靶材的制备中也具有重要的潜在应用价值。(3)射频溅射多晶石榴石薄膜研究：研究了衬底、溅射工艺及原位晶化工艺对薄膜磁性能的影响；针对不同的衬底，摸索出了最佳制备工艺条件，得到了结构致密、表面平整、可调饱和磁化强度的薄膜，发现在GGG(111)衬底上，控制适当的工艺，可原位外延出单晶石榴石薄膜。(4)快速循环晶化(RRTA)理论及工艺研究：建立快速循环纳米晶化量子动力学模型，分析了石榴石多晶薄膜在晶化过程中的成核、生长的基本规律，理论和实验结果证实该方法可以有效细化薄膜晶粒，大大提高薄膜的磁光效应，使法拉第效应成倍增大。(5)静磁表面波滤波器的理论和实验研究：首先建立了静磁表面波滤波器损耗理论模型，分析了石榴石薄膜的厚度、饱和磁化强度及铁磁共振线宽等参数对滤波器损耗的影响；其次，建立了双磁性层结构对静磁表面波的色散抑制理论；最后，利用液相外延的单层和双层LuBiIG石榴石薄膜，分别实现了性能优良的静磁表面波带通滤波器。器件频域4．0—5．5GHz，带宽180±10MHz，插入损耗(?)8．0dB(应用双层色散抑制结构后，插损可达6．0dB以下)，带外抑制(?)35dB。(6)微波铁氧体环行器薄膜化的可行性研究：从环行器的设计理论出发，研究了基片和薄膜厚度对环行器性能的影响。结果表明在较低频段(1．0-3．0GHz)，经过进一步完善薄膜的制备工艺，薄膜环行器的实现是可能的；而在高频段存尚存在一定的制约因素。(7)石榴石薄膜的THz波导特性研究：研究了液相外延LuBiIG单晶石榴石薄膜和射频磁控溅射多晶石榴石薄膜在THz波段的透射特性。结果发现：该种石榴石薄膜在THz波段(0．1—3THz)有着很小的吸收损耗系数，最小值为0．01---0．2／cm之间，是一种非常有潜力的THz波导传输材料。(8)石榴石薄膜型平面波导开关基础研究：基于Bi：YIG薄膜材料的巨磁光法拉第效应和无铅液相外延石榴石薄膜的大法拉第效应，建立了波导型磁光开关的理论模型，并利用磁光传输理论，分析了影响磁光开关性能的一系列因素，最终成功实现了波导型磁光开关。其基本性能参数为：插入损耗：0．6-3．0 dB，开关速度：40μs-2ms之间。更多还原

【Abstract】 With the development of integrated devices in radio frequency(RF), microwave, terahertz wave and optical band, an idea has been brought forward, that is how can we investigate a kind of film using in microwave, terahertz (THz) and optical devices and realize the integrated devices in range from microwave to optical band. The main work of this thesis is the verification of the imagination. Firstly, three kinds of garnet films were designed based on its low propagating loss in microwave devices and magneto-optical devices and potential application in terahertz band; Secondly, several kinds of garnet films were realized by liquid phase epitaxy (LPE) method with lead-free flux and RF magnetron sputtering, and their properties and application in microwave, terahertz and optical band were analyzed in detail; Finally, the application of garnet films using in these devices were investigated, the test results show that these garnet films have good performance in three wave band and it is very important to future integrated devices.Based on the abovementioned ideas, many investigations have been done on basic theories, material preparing technologies and devices designing. In this thesis, the main work is just as follows,(1) The investigation of LuBiIG mono-crystal garnet film by buffer LPE method with lead free flux has been done. The microstructure, surface condition and deficiency controlling technologies of large area film were studied in detail. The buffer LPE method which is suitable for lead free flux technology has been brought forward, and the point is the effect of axis of GGG substrate and film growth rate to the films qualities. At last, the film combined with both superior magnetic and magnetic-optical properties together is obtained by optimizing LPE technology, and the lattice of the thin film has a good match with the GGG (111) substrate and good surface. The saturation magnetization (Ms) of the film is about 1562Gs, the Faraday rotation is 1.6～2.0deg/μm and the minimum FMR linewidth value is 2△H=5.1Oe.(2) The application of microwave sintering (MS) technology in ferrite garnet materials has been carried out. The MS method has been applied in garnet target sintering and the garnet target with good performance is obtained by optimizing sintering curve and temperature. Experiments show that microwave sintering (MS) treated YIG materials possess excellent properties in target density, dielectric loss, dielectric constant and magnetic loss besides high efficiency and saving time. If the room with even temperature in MS oven is enlarged, the MS method is not only making for improving performance of garnet substrate using in microwave devices, but also voluble for preparing sputtering targets.(3) The investigation of garnet films by RF magnetron sputtering has been done in this thesis. The effects of substrate, sputtering parameters, post-treated technology to the film performance have been studied in detail. The films with dense structure, smooth surface condition and adjustable saturation magnetization have be prepared by optimized technology. Additionally, the monocrystal garnet film can be obtained on GGG substrate by controlling the sputtering and annealing technology.(4) The investigation of rapid recurrent thermal annealing (RRTA) theories and technology has been done. The RRTA nanometer crystallizing quantum kinetics model was created and the rules of crystal core forming and growth in the process of crystallizing were analyzed. The results show that the crystal grains scale of garnet films can be decreased efficiently by RRTA method, which leading to the increasing of magneto-optical effect and the Faraday Angle is doubled.(5) The investigation of theories and experiments of magnetostatic surface wave (MSSW) filter has been done in chapter 4. Firstly, the insertion loss model of MSSW filter has been created, and the effect of the thickness of garnet film, saturation magnetization and linewidth to the insertion loss of the filter have been analyzed in detail; Secondly, the dispersion restrain theory with the double magnetic layer structure has been created; Finally, the filters with good performance were realized with LuBiIG film. The filter parameters are as follows, the center frequency is between 4.0 and 5.5GHz, the pass bandwidth is 180±10MHz, insertion loss is smaller than 8.0dB (this value can be reduced to 6.0dB with double magnetic layer structure), and out-band rejection is bigger than 35dB.(6) The feasibility investigation of microwave ferrite film circulator has been done. Based on circulator design theory, the effect of thickness of substrate or film to the circulator performance has been investigated. The results show that the film circulator can be realized from 1.0GHz to 3.0GHz by perfecting garnet film preparing technology, however, it is still needs a long time to be realized because of its restriction conditions in high frequency band.(7) The investigation of THz response of garnet film has also been done. The transmittance performance of LuBiIG garnet film by LPE method and polycrystalline garnet film by RF magnetron sputtering in THz frequency range has been investigated and the results show that garget film is with low absorbance coefficient at THz band, and minimum value is 0.01- 0.2/cm, and garnet films are potential materials in THz wave-guide application.(8) At last, the investigation of garnet film plane wave-guide switch has been done. Based on the giant magneto-optical (MO) Faraday Effect of Bi :YIG garnet, the model of wave-guide MO switch has been created and the factors which affecting the performance of the switch have been analyzed by applying MO transmittance theory, and the wave-guide MO switch has been realized at last. Its insertion loss is between 0.6 and 3.0dB, on-off rate is between 40μs and 2ms.更多还原