【作者】 程培红；

【导师】 杨德仁； 阙端麟；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2009， 博士

【摘要】 随着建立在硅材料基础上的大规模集成电路的不断发展,过高的互连和集成度带来了信号延迟和器件过热的问题,给以大规模集成电路为代表的微电子工业的持续发展带来了很大的困难,而硅基光电子集成则是解决这一难题的理想途径。但是,高效率的硅基发光材料和器件国际上依然没有解决。而将金属表面等离子体用于增强发光材料和器件量子效率,则是研究的热点。本文将表面等离子体用于提高硅基发光材料和器件的发光效率,不仅在表面等离子耦合发光的机理研究上有重要的理论探索意义,而且在硅基光电子领域有良好的应用前景。本文制备了金属岛膜和核-壳阵列结构,研究了影响其形貌和表面等离子体共振特性的因素,在此基础上将金属银岛膜用于增强硅基ZnO薄膜和富硅氮化硅薄膜的发光强度,并且详细研究了影响材料与表面等离子体耦合发光的因素以及耦合作用机理。取得如下有创新意义的结果:(1)利用磁控溅射法制备了Ag岛膜,掌握了调节其表面等离子体共振特性的各种参数。研究通过不同热处理工艺,改变银岛膜的形貌,进而调节其表面等离子共振波长。研究发现:200℃的快速热处理可使共振波长有较大蓝移,在不同温度下的常规热处理可以连续调节银岛膜的表面等离子共振波长。(2)利用聚苯乙烯球(PS)为模板,制备了Ag和Au的核-壳结构阵列,掌握了调节其表面等离子体共振特性的各种参数。实验发现,随着溅射时间增加,壳层变厚,其偶极表面等离子体共振频率蓝移。在利用热处理的方法去除PS球模板后,金属核-壳的介电环境发生变化,进而偶极等离子共振频率发生蓝移,实验还确定了热处理去除模板的适宜温度和所需时间。(3)利用Ag岛膜增强了ZnO薄膜的带间发光,确定了能量传递-散射的表面等离子体耦合机理。ZnO带间发光和缺陷发光分别与Ag岛膜的面外和面内局域表面等离子体共振模式耦合,导致了带间和缺陷发光荧光强度变化的不同,并且发现可以通过调节表面等离子共振达到控制耦合发光强度的目的。研究了Ag颗粒大小、探测方向、ZnO薄膜的厚度以及温度等因素对Ag岛膜耦合增强ZnO薄膜发光的影响,并且分析了不同条件下耦合发光的机理。(4)发现了Ag岛膜耦合增强ZnO薄膜发光对衬底折射率的依赖。通过理论计算,指出其原因主要是由于高折射率衬底会给体系引入衬底模式,该模式会对耦合进入表面等离子体模式的能量造成竞争,进而影响表面等离子体经散射作用而辐射出去的能量。近一步地,实验设计了四层结构,避免了衬底模式对能量的损耗,达到了表面等离子体耦合增强硅基ZnO薄膜发光的目的。(5)利用Ag岛膜的局域表面等离子体增强了富硅氮化硅薄膜的发光。研究结果表明,相对于银岛散射的辐射增强作用,表面等离子体增强激发效率对富硅氮化硅薄膜的荧光增强起到了决定作用。通过研究不同发光波长的氮化硅薄膜与Ag岛膜的耦合发光,指出:其荧光的增强因子不但与银岛的尺寸有关,还与发光波长与Ag岛膜的表面等离子共振带的光谱位置有关,其中后者还会影响耦合增强后的富硅氮化硅薄膜的荧光峰位。更多还原

【Abstract】 With the rapid development of large scale integrated electronic circuit based on the silicon materials, signal delay induced by over-high interconnect and over-heat of device is becoming serious problems. It poses a dramatic difficulty to the continuous development of the microelectronic industry represented by integrated electronic circuit. Optoelctronic system is a potential solution to this problem, but silicon makes a poor material for light emitter due to its indirect band structure which limits the application in optoelctronics. So obtaining high-efficiency silicon-based light emitting mateials and devices is very important. Suface Plasmon at the metal interface can increase the rediative decay rates of the light emitter thanks to the high localized electromagnetic field at resonance. Moreove, by matching the wavevector of surface plasmon and light radiation using scattering, the energy lost at the metal electrode can be recovered which will improve the efficiency of the light emitting devices. Then using suface plasmon to increase the light emission has become a hot topic in recent years. Evidentsly, using surface plasmon to enhance the light emission is expected to find wide potential applications in silicon-based light emitters.In this dissertation, metal island films and core-shell structure were produced and the factors that affect its morphology and suface palsmon resonance properties were investigated. Then the light emission of ZnO and silicon rich silicon nitride films was enhanced by coupling with Ag island films. The coupling mechanism and the factors affecting the coupling were analyzed. The primary significant results were summarized as follows:(1) Ag island films were prepared by sputtering, and the morphology and surface plasmon were found dependent on the sputtering time and temperature. Thermal processing changed the morphology of Ag island films and then tuned the surface plasmon resonance wavelength. Large blueshift can be obtained by rapid thermal processing at 200℃, and conventional thermal processing at different temperature can tune the resonance wavelength continuously.(2) Ag and Au core-shell arrays were prepared by sputtering using PS sphere as templates. The core-shell morphology and surface palsmon resonance were changed by sputtering time. With the increases of sputtering time, the shell thickness increased and the dipole surface Plasmon blueshifed. The PS template can be removed by thermal processing. The dielectric environment was changed by PS removal which led to the blueshift of the dipole resonance.(3) The band gap emission of ZnO films was enhanced and the defect emission was quenched by coupling with the surface Plasmon of Ag island films. It was found that the band emission and defect emission were coupled with out-of-plane and in-plane surface plasmon resonance mode of Ag island films respectively. The absorption of the in-plane surface plasmon mode induced the quenching of the defect emission and it can be recovered by tuning the in-plane resonance mode using thermal processing. The influence of Ag island size, detection directions, the thickness of ZnO films and the temperature on the surface plasmon coupled emission enhancement was investigated, and the coupling mechanisms under different conditions were elucidated.(4) The Ag island films coupled emission enhancement of ZnO films was found dependent on the substrate. Theoretical computation results shows that when using high refractive index substrate, the substrate mode has a competition with the surface palsmon mode in energy, which then affect the energy of surface plasmon radiative scattering, leading to the emission quenching. The four-layer structure which avoided the energy lost to substrate mode was designed to enhance the emission of silicon based ZnO film.(5) The photoluminescence of silicon rich silicon nitride films was enhanced by coupling with surface plasmon of the Ag island films and the coupling mechanism of the excitation and radiative process was investigated. The results show that the surface plasmon enhanced emission was more decided by excitation efficiency enhancement than radiative scattering enhancement. It was found that the photoluminescne enhancement was not only dependent on the Ag island size, but also on the relative spectral position between the emitting wavelength and the surface plasmon resonance band, and the latter also influenced the emission band position of the silicon rich silicon nitride.更多还原