【摘要】 在α-Al₂O₃（0001）表面研究了N,N’-二戊基-3,4,9,10-苝二甲酰亚胺（PTCDI-C₅）薄膜形貌与基底温度之间的关系.在背景真空度低于6×10-7Pa的超高真空腔中,利用分子束外延方法在基底上生长标称厚度为0.6 nm的PTCDI-C₅薄膜,薄膜生长过程中的基底温度分别被控制在25℃、37℃和61℃.生长结束后,利用原子力显微镜（AFM）轻敲模式在大气环境下对薄膜形貌进行离线表征.AFM图像显示在Al₂O₃基底表面,PTCDI-C₅分子形成岛,而且PTCDI-C₅岛的排列与基底温度之间呈现一定关系.本文实验条件下,在25℃和37℃之间存在一个基底温度阈值.在薄膜生长过程中,当基底温度低于此温度阈值时,PTCDI-C₅岛在基底表面随机排列;相反,当基底温度高于此温度阈值时,PTCDI-C₅岛沿着Al₂O₃（0001）表面的台阶边缘分布.更多还原

【Abstract】 The morphologies of N,N’-dipenthyl-3,4,9,10-perylene tetracarboxylic diimide（ PTCDI-C₅）thin films on the α-Al₂O₃（ 0001） substrate were investigated as a function of substrate temperature. The PTCDI-C₅ thin films with a nominal thickness of 0. 6 nm were deposited on the substrate by molecular beam epitaxy in an ultrahigh vacuum chamber with a base pressure lower than 6 × 10-7 Pa. During deposition,the substrate temperature was controlled at 25 ℃,37 ℃,and 61 ℃,respectively. The morphologies of PTCDI-C₅ thin films were characterized ex-situ by atomic force microscope（ AFM） in the tapping mode at room temperature. AFM images showed that the PTCDI-C₅ molecules formed islands on Al₂O₃ substrate,and the arrangement of PTCDI-C₅ islands showed dependence on the substrate temperature during deposition. Under our experimental conditions,a substrate temperature threshold between 25 ℃ and37 ℃ was observed. When the substrate temperature during deposition was lower than the temperature threshold,the PTCDI-C₅ islands randomly distributed on the surface. On the contrary,when the substrate temperature during deposition was higher than the temperature threshold,the PTCDI-C₅ islands aligned themselves along the step edges on the Al₂O₃（ 0001） surface.更多还原