氨流量对制备富硅-氮化硅薄膜微结构演化的影响

Effect of Ammonia Flow Rates on Microstructure Evolution of Silicon-rich Silicon Nitride Thin Films

利用热丝化学气相沉积法制备富硅-氮化硅薄膜,研究氨气流量对薄膜微结构的影响。实验中将热丝温度、衬底温度、沉积压强、硅烷流量及衬底与热丝间距等实验参数优化后,改变氨气流量,制备了一系列SiN x薄膜样品。结果发现,氨气流量增加时,薄膜中Si-N键的形成却受到抑制,薄膜带隙展宽,缺陷态也随之增加。在光致发光谱480~620 nm范围内,观察到发光峰有明显的红蓝移现象,认为薄膜中有硅量子点的存在,缺陷态发光强度相对硅量子点的发光强度逐渐增强,为进一步制备在SiN_(x)薄膜中包埋硅量子点材料提供了依据。

A silicon-rich silicon nitride film was prepared by hot-wire chemical vapor depositionto study the effect of ammonia flow rates on microstructure evolution of thefilmsin the paper.In the experiment,the ammonia gas flow was a variable parameter,with the other experimental parameters,such as the hot wire temperature,substrate temperature,deposition pressure,silane flow rateand the distance between the substrate and hot wire in constant and under optimized conditions.The results showed that the main bonding structure in the thin film was Si-N bondaccompanied with stable Si-Si bond,suggesting that the thin film wasa silicon nitride film and had a silicon-rich phase.Changing the ammonia gas flow indicated that the formation of Si-N bonds in the thin film was inhibited,the band gap widened,and the defect state increased with the increase of N atoms.The photoluminescence spectroscopy(PL)found that there were both defect state luminescence peaks and silicon quantum dot luminescence peaks in the thin films,indicative of the existence of silicon quantum dots in the film.Meanwhile,the increase of ammonia flow ratemadethe luminescence intensity of defect statesenhancedgradually compared with the luminescence intensity of silicon quantum dots.Theresearch provided a basis for further preparation of silicon quantum dots embedded in the SiN_(x)thin films.