【作者】 乌仁图雅；

【导师】 周炳卿；

【作者基本信息】 内蒙古师范大学 ， 光学， 2016， 硕士

【摘要】 由于量子尺寸效应,包含硅量子点的富硅-氮化硅薄膜材料表现出了优异的发光性能。同时,镶嵌在富硅-氮化硅薄膜材料中的非晶硅量子点在短波范围具有好的发光效率,且发光波长连续可调,使得其在光电子器件中具有非常好的应用前景。将包含硅量子点的富硅氮化硅材料引入到太阳能电池中,可以极大地增强对太阳光的有效吸收,提高太阳电池的光电转换效率,成为未来高效的第三代硅基量子点太阳能电池最有可能的竞争者。基于这些优点,本文进一步的研究了沉积参数对包含非晶硅量子点的富硅-氮化硅薄膜结构及性质的影响,以便优化出最佳的制备工艺参数应用于材料的制备工艺中。采用了等离子体化学气相沉积(PECVD)方法制备包含非晶硅量子点的富硅-氮化硅薄膜材料,并利用傅里叶变换红外光谱,X-射线衍射谱,紫外-可见光吸收谱,光致发光谱,扫描电子显微镜等手段来表征与分析所制备样品的结构及特性。样品沉积时采用的气源分别为纯度为99.999%以上的SiHH4、NH3、N2和H2。本论文主要的实验研究结果如下：1.以SiHH4、NH3、N2为反应气源,研究改变N2流量对富硅氮化硅薄膜结构及性质的影响。实验结果表明,随着氮气流量的增加,薄膜的键密度及各原子含量增加,伴随着折射率增大,薄膜光学带隙逐渐减少,薄膜有序度提高,但过量的增加氮气反而起到稀释作用,阻止氮气掺入到薄膜中,导致缺陷态增多,价带及导带之间距离减小,导致薄膜的带尾吸收边变宽,光学带隙减小,有序度降低,影响薄膜的致密度。2.以SiHH4、NH3和N2为反应气源,通过改变射频功率制备富硅-氮化硅薄膜材料。实验表明,随着射频功率的逐渐增加,薄膜Eg缓慢减小、有序度增加,样品中的硅氢键、氮氢键缓慢减小,硅氮键增多。分析结果发现,适量的增加射频功率有利于提高样品反应速率,使薄膜有序度增加,致密性增强,提高薄膜质量,但过高的射频功率会使薄膜质量变差。3.以SiHH4、NH,、H2为反应气源,改变氢流量制备包含非品硅离子点的富硅-氮化硅薄膜材料。实验发现,适量的提高氢气流量,可提高反应过程中H离子与Si、N悬挂键的键合几率,起到钝化薄膜悬挂键的作用。当H2流量在10 sccm跟20 sccm之间时,H原子主要钝化薄膜悬挂键,使缺陷态减少,从而缺陷态发光减弱,薄膜光学带隙缓慢展宽。随着增加H2流量,薄膜中的氮原子同时持续增加,将伴随着缺陷态再次增多,辐射加强,导致光学带隙迅速展宽。当Hz流量达到30 sccm时,薄膜中的氮化硅晶粒增大,数目增多,缺陷态所引起的发光消失,出现了由非晶硅量子点团簇引起的发光现象,说明样品中出现了非晶硅量子点团簇。因此,适量的提高氢气流量能够钝化薄膜缺陷态,并实现从富硅-氮化硅向Si3N4相转变的过程中形成氮化硅基质包埋的非晶硅量子点团簇结构。更多还原

【Abstract】 Silicon nitride is considered to be a greater prospect of silicon-based light emitting material because of its many excellent properties, so widely used in many fields. Based on these advantages, this text further to research the effect of deposition parameters on the structure and properties of silicon-rich silicon nitride and research how to optimize its luminescence properties, in order to regulate the best preparation technology parameters, used in the film production process. Silicon-rich silicon nitride thin films were deposited by plasma enhanced chemical vapor deposition method using SiH4, NH3,N2 and H2 as reaction gas. The structures and properties of the materials were characterized by Fourier transform infrared absorption spectroscopy, ultraviolet-visible transmission spectra, XRD and photoluminescence spectra, Scanning electron microscope, respectively. The results showed that:1. Using SiH4, NH3,N2 and H2 as reaction gas, researching the effect of changing H2 flow rates on the structure and properties of silicon-rich silicon nitride. The experimental results show that, properly increasing nitrogen flow rate helps to improve the bonding probability of thin film, the order degree of films improve gradually, at the same time becouse of its refractive index is close to ideal so it used to make minus reflection film. But increas too much nitrogen flow will prevent the nitrogen atoms into the film, which resulting in the reduction of defect states, damage film quality.2. Silicon-rich silicon nitride thin films were deposited by plasma enhanced chemical vapor deposition method using SiH4 NH3 and N2 as reaction gas source with changing of radio-frequency power. The structures and properties of the film materials were characterized by Fourier transform infrared absorption spectroscopy, ultraviolet-visible transmission spectra and SEM, respectively. The results showed that, with radio-frequency power increasing, the bandgap width of the film materials decrease slowly, the order degree of films improve gradually. and the Si-N、N-H bonds in the films decrease, with increasing of the Si-N bonds gradually. Analysis of the results find that, properly increasing radio-frequency power is beneficial to the enhancing of the ion reaction rate in films, the improving of film order degree, the enhancing of film compactness, the getting better of film quality. But the outrageous radio-frequency power will damage film quality.3. Silicon-rich silicon nitride thin films were deposited by plasma enhanced chemical vapor deposition method using SiH4, NH3 and H2 as reaction gas source with changing of H2 flow rates. The structures and properties of the materials were characterized by Fourier transform infrared absorption spectroscopy, ultraviolet-visible transmission spectra, XRD and photoluminescence spectra, respectively. The results showed that, properly increasing hydrogen flow rate helps to improve the bonding probability between hydrogen ion and Si and N dangling bonds in deposition process. Thus hydrogen play an important role in passivation of dangling bonds. When hydrogen flow rates change from 10 to 20sccm, hydrogen ions mainly play a role of dangling bond passivation, which resulting in the reduction of defect states and weakening of defect state photoluminescence effect, so that bandgap of the film widening slowly. When hydrogen flow rates increase, the amounts of nitrogen atoms grow up continuously, with the increase of defect states again, enhancement radiation, and leading to the optical bandgap rapidly broadening. When the hydrogen flow rates is 30sccm, silicon nitride grain size and numbers increase in the films, photoluminescence effects of defect states disappear, the luminescence effects caused by amorphous silicon cluster quantum dots in the silicon nitride matrix appear. It indicated that amorphous silicon cluster quantum dots create in the films. Therefore, properly increasing hydrogen flow rate helps to passivate films and grow out of the structures of amorphous silicon cluster quantum dots embedded amorphous silicon nitride matrix in the process of structure transition from rich silicon nitride to Si3N4 phase.更多还原