衬底温度对共溅射法制备的Cu_2ZnSnS_4薄膜晶粒生长的影响

Effect of Substrate Temperature on Grain Growth of Cu_2ZnSnS_4 Thin Film Prepared by Co-sputtering Method

研究了衬底温度对采用Cu_2ZnSnS_4靶和Cu靶共溅射制备的Cu_2ZnSnS_4薄膜晶粒生长的影响。采用拉曼光谱、X射线能量色散谱仪、扫描电子显微镜和紫外-可见-近红外分光光度计对在不同衬底温度条件下制备的Cu_2ZnSnS_4薄膜的元素比例、形貌以及光学带隙进行了表征与分析。结果表明制备的Cu_2ZnSnS_4薄膜晶粒生长遵循不同规律。室温衬底条件下制备的Cu_2ZnSnS_4薄膜晶粒生长遵循两步法,导致颗粒尺寸和元素分布不均;而在120~200℃衬底温度条件下制备的Cu-Zn-Sn-S预置层在溅射过程中已有Cu_2ZnSnS_4晶粒形成,这些晶粒在后续硫化生长过程中起到形核点的作用,促进了Cu_2ZnSnS_4晶粒的长大与元素的均匀分布。随着衬底温度的升高,Cu-Zn-Sn-S预置层及由此制备出的Cu_2ZnSnS_4薄膜的结晶性变好,Cu_2ZnSnS_4薄膜的带隙先升高后减小至1.55eV。

The effect of substrate temperature on the grain growth of Cu_2ZnSnS_4 thin film prepared by co-sputtering of Cu_2ZnSnS_4 and Cu targets is studied.The chemical composition,morphology and band gap of Cu_2ZnSnS_4 thin films are characterized by Raman,energy dispersive spectrometer（EDS）,scanning electron on icroscope（SEM）and UV-Vis-NIR spectrometer,respectively.The results show that the formation of Cu_2ZnSnS_4 thin film follows different mechanisms.When the substrate is under room temperature,the growth of Cu_2ZnSnS_4 grains follows the two-step mechanism,leading to the inhomogeneous distributions of particles and element of Cu_2ZnSnS_4 thin film.However,Cu_2ZnSnS_4 grains appear during the co-sputtering process in Cu-Zn-Sn-S precursor at substrate temperature from 120—200 ℃,which act as nucleation seeds to promote the growth and homogeneous distribution of Cu_2ZnSnS_4 grains in the post sulfurization process.With increasing substrate temperature,the crystallinity of Cu-Zn-Sn-S precursor and Cu_2ZnSnS_4 thin film becomes better,and the band gap of Cu_2ZnSnS_4 thin films first increases then decreases to 1.55 eV.