石墨烯是近年发现的一种新型多功能材料.在合适的衬底上制备石墨烯成为目前材料制备的一大挑战.本文利用分子束外延(MBE)设备,在Si 衬底上生长高质量的SiC 缓冲层,然后利用直接沉积C原子的方法生长石墨烯,并通过反射式高能电子衍射(RHEED)、拉曼(Raman)光谱和近边X 射线吸收精细结构谱(NEXAFS)等实验技术对不同衬底温度(800、900、1000、1100 °C)生长的薄膜进行结构表征.实验结果表明,在以上衬底温度下都能生长出具有乱层堆垛结构的石墨烯薄膜.当衬底温度升高时,碳原子的活性增强,其成键的能力也增大,从而使形成的石墨烯结晶质量提高.衬底温度为1000 °C时结晶质量最好.其原因可能是当衬底温度较低时,碳原子活性太低不足以形成有序的六方C-sp2环.但过高的衬底温度会使SiC 缓冲层的孔洞缺陷增加,衬底的Si 原子有可能获得足够的能量穿过SiC薄膜的孔洞扩散到衬底表面,与沉积的碳原子反应生成无序的SiC,这一方面会减弱石墨烯的生长,另一方面也会使石墨烯的结晶质量变差.%Graphene is a newly discovered material with many functions. The preparation of graphene on suitable substrates is a challenge in the material preparation field. In this paper, graphene thin films were grown on Si substrates covered with SiC buffer layers (SiC/Si) by the direct deposition of carbon atoms using molecular beam epitaxy (MBE) equipment. The structural properties of the samples produced at different substrate temperatures (800, 900, 1000, 1100 ° C) were investigated by reflection high energy electron diffraction (RHEED), Raman spectroscopy and near-edge X-ray absorption fine structure (NEXAFS). The results indicate that the thin films grown at all temperatures exhibit the characteristics of graphene with a turbostratic stacking structure. As the substrate temperature increases the crystalline quality of the graphene improves. However, a very high temperature decreases the quality of graphene. The best graphene films were obtained at a substrate temperature of 1000 °C. This is due to the low substrate temperature resulting in a too low carbon atom activity for the formation of an ordered six-member ring of C-sp2. When the substrate temperature was too high the silicon atoms in the substrate became so active that silicon atoms diffused to the surface of the sample through SiC buffer defects and they bonded to the depositing carbon atoms, which resulted in a lower crystallization quality of the carbon layers.
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