稀土离子和硅掺杂氧化锌薄膜的荧光性质研究

发布时间：2018-03-23 01:38

  本文选题：氧化锌薄膜　切入点：铒荧光　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,随着光纤通信技术的不断发展,铒(Er)掺杂的半导体材料引起了研究者的极大兴趣。这是因为,Er离子在1540nm处有很好的的荧光性质,而这一波段正好是光纤通讯的最低损耗窗口之一。然而,1540nm的辐射跃迁对于Er离子来说,属于其电子壳层4f层组态内的跃迁(简称f-f跃迁),是不符合宇称守恒定则的,即该跃迁在常规情况下是禁戒的。因此,数以万计的研究团队针对这个问题作出了巨大的努力,并提出了相应的解决方案。在众多解决方法中,我们发现,如果将Er离子置于环氧环境中,并且以宽禁带半导体作为宿主的话,那么该禁戒就能够被打破——f-f跃迁不仅能够实现,而且还可能得到优良的荧光性质。考虑到这两个方面,我们最终选择了氧化锌(ZnO)作为宿主,而且在磁控溅射生长ZnO:Er薄膜的时候通入一定量的氧气(O2)。ZnO是一种宽禁带直接带隙半导体材料,禁带宽度3.37eV(常温),而且具有较大的激子结合能(60meV),它在短波长发光二极管、激光器和太阳能电池等方面应用广泛。在本论文中,我们主要运用磁控溅射方法探索了 ZnO:Er薄膜的生长条件,并研究了薄膜厚度、退火温度、衬底类型以及硅(Si)离子注入等条件对薄膜中Er离子红外荧光的影响,并在后期重点分析了衬底Si扩散对其荧光的抑制作用。在实验过程中,我们运用卢瑟福背散射的实验方法测量并计算了薄膜的厚度及组分,依托X射线衍射谱分析了薄膜的结晶性质,至于薄膜的表面形貌,我们则是利用光学显微镜和原子力显微镜等进行观察。当然,所有的红外光谱都是由532nm的绿光激光器作为泵浦源,通过铟镓砷探测器接收信号,经过一定处理而得到的。通过分析,我们发现,一般情况下,以Si-SiO2为衬底,薄膜的厚度越厚,退火到250℃左右,Er-1540nm的荧光强度会更强。当退火温度达到550℃时,Er-1540nm荧光会减弱,一方面是和能量传输相关的如缺陷能级等"中间态"少了,另一方面是因为550℃的退火环境会诱发比较严重的衬底Si扩散,这些扩散进薄膜的Si会"抢夺" Er的能量用于自身的发光、发热等,从而降低了 Er的荧光效率。关于这一过程,我们首次建立了相应的能量传输机制模型,并具体分析了 Si和Er能量传输效率低的原因。此外,我们还向ZnO:Er薄膜中注入了不同剂量的Si离子,发现当注入剂量远大于薄膜中的Er含量时,Er-1540nm的荧光重归禁戒。但是样品经过高温退火(氮气环境)后,随着薄膜损伤的恢复,该禁戒又会被打破。这些实验结果及结论,对于Si基光电子材料的制作、集成等方面具有一定的参考意义,也为稀土发光理论的大楼添砖加瓦。
[Abstract]:In recent years, with the development of optical fiber communication technology, erbium Er-doped semiconductor materials have attracted great interest of researchers. This is because the er ion has good fluorescence properties at 1540nm. This band is one of the lowest loss windows for optical fiber communication. However, for er ion, the radiation transition at 1540nm belongs to the transition within the 4f configuration of the electron shell (f-f transition), which does not conform to the parity conservation rule. So tens of thousands of research teams have made tremendous efforts to address the problem and come up with solutions. Among the many solutions we have found, If the er ion is placed in the epoxy environment and the wide band gap semiconductor is used as the host, the forbidden ring can be broken. The f-f transition is not only possible, but also possible to obtain excellent fluorescence properties. Zinc oxide (ZnO) was chosen as the host, and a certain amount of oxygen O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ (2 +) was added to the ZnO:Er thin films grown by magnetron sputtering, which is a wide bandgap semiconductor material. The band gap is 3.37 EV (room temperature) and has a large exciton binding energy of 60 meV. It is widely used in short wavelength light-emitting diodes, lasers and solar cells. We have investigated the growth conditions of ZnO:Er thin films by magnetron sputtering, and studied the effects of the thickness of the films, annealing temperature, substrate type and Si + implantation on the infrared fluorescence of er ions in the films. The inhibitory effect of substrate Si diffusion on its fluorescence was analyzed in the later stage. In the process of the experiment, the thickness and composition of the films were measured and calculated by Rutherford backscattering. The crystalline properties of the films were analyzed by X-ray diffraction, and the surface morphology of the films was observed by optical microscope and atomic force microscope. All the infrared spectra are obtained by using the green laser of 532nm as the pump source, the signal is received by the indium gallium arsenic detector and processed to a certain extent. Through the analysis, we find that, in general, the thickness of the thin film is thicker on the Si-SiO2 substrate. The fluorescence intensity of Er-1540nm annealed at about 250 鈩，

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