氮流量对热丝制备富硅-氮化硅薄膜的结构及性质影响

Effect of Nitrogen Flow Rates on The Structures And Properties of Silicon-rich Silicon Nitride Thin Films Prepared By Hot Wire Method

采用热丝化学气相沉积法,以Si H4、NH3、N2作为反应气源,通过改变氮气流量来制备富硅-氮化硅薄膜材料。通过傅里叶红外变换谱、紫外-可见光吸收谱、光致发光谱、扫描电镜分别对薄膜的结构、带隙宽度、发光特性及表面形貌进行表征与分析。实验结果表明,随着氮气流量增加,薄膜中N原子含量减少,镶嵌在氮化硅母质中的硅团簇增大,Si-N键的键密度逐渐减少,薄膜的光学带隙Eg和带尾能EU呈现减小的趋势,薄膜有序度增加,且由氮悬挂键所引起的缺陷态发光峰增强。当氮气流量为30sccm时,Si-N键的非对称伸缩模式和Si-H键伸缩振动模发生了蓝移,当[N2]/[NH3]流量比小于5:1时,氮气流量对薄膜中氮含量的影响非常明显,适当地降低氮流量有利于制备出富硅-氮化硅薄膜。

Silicon-rich silicon nitride thin films were deposited by hot wire chemical vapor deposition method based Sill4, NH3, N2 as reaction gas source with changing nitrogen flow rates. The structure, band gap width, light- emitting performance and surface morphology of thin films were characterized and analyzed by Fourier transform infrared absorption spectroscopy, ultraviolet-visible spectra, photoluminescence spectra and SEM etc, respectively. The results showed that nitrogen content in the films decreases, silicon cluster grain buried in silicon nitride matrix grow up, Si-N bond density gradually decreases, optical band gap width Eg and the band tail energy EU tend to decrease, atomic order degree in the films increase, with increase of nitrogen flow rates. And photoluminescence peak cited by nitrogen dangling bond defect states enhance. When nitrogen flow rate is 30sccm, Si-N bond of asymmetric stretching mode and Si-H bond of stretching vibration mode show a blue shift. When [N2] / [NH3] ratio is less than 5： 1, influence of nitrogen flow rate on nitrogen content in films is more obvious. Therefore, properly reducing nitrogen flow rate helps to prepare a rich silicon nitride thin film materials.