碳化硅超薄膜热分解法石墨烯的制备及其气敏性能研究

Graphene is a new kind of low-dimensional carbon material, which can be regarded as a planar two-dimensional crystal of carbon atoms axially sectioned from carbon nanotube. Individual adsorbed gas molecules can be sensitively sensed via graphene's exceptional integer quantum Hall effect. Thus the gas sensing performance of graphene is much better than that of the current existing semiconductor gas sensor. Meanwhile, graphene also has the unique advantage that is compatible with the silicon planar process. Based on these points, this proposal investigate on the preparation of silicon carbide ultra-thin film derived graphene, and its rapid gas sensing performance for toxic gases (such as CO, NH3, NO, etc.) in ppm~ppb level to meet the demand in the fields of environmental monitoring and medical diagnostics. The main contents of this proposal include silicon carbide ultra-thin films growth, epitaxial graphene via thermal decomposition, topology design of graphene ribbon, the sensor microstructure design and the device verification as well. The proposal innovation is the Si-C double atomic layer deposition of silicon carbide, graphene growth via thermal decomposition, and graphene decoupling by hydrogen intercalation to control the background carrier concentration and to improve the carrier mobility. It is expected that this work not only has a great scientific significance for the further study of epitaxial graphene on silicon carbide thin films, at the same time also of great significance for the development of the field of gas sensing.

石墨烯是一种新型低维碳材料，它可以视为碳纳米管沿轴向剖开后成平面状的二维碳原子晶体。利用它的异常整数量子霍尔效应，可以灵敏地感测单个气体分子的吸附，其气敏特性远高于当前半导体气体传感器。同时，石墨烯还具有与硅平面工艺相兼容的独特优势。本项目以此为出发点，研究以碳化硅超薄膜为基体的石墨烯的制备及其气敏特性，探索它对ppm～ppb量级有害气体（如CO、NH3、NO等）的检测性能，以满足环境监测、医疗诊断等领域的需求。项目的研究内容包括碳化硅超薄膜的制备、热分解法制备石墨烯、条带石墨烯的拓扑结构设计，在这个基础上设计传感器微结构并通过器件验证。项目创新性体现在按Si-C双原子层沉积碳化硅，随后通过热分解生长石墨烯，利用氢插层的方法将石墨烯退耦，以控制背景载流子浓度、提高迁移率。这项工作的开展，不仅对碳化硅超薄膜外延石墨烯的进一步研究具有极大的科学意义，同时对气体传感领域的发展也具有重要意义。

在碳化硅衬底上外延生长石墨烯实现石墨烯在微电子领域中应用,利用感应加热的高温CVD设备,先在4H-Si C衬底上外延生长一层2~10μm厚的碳化硅,然后直接再在外延碳化硅上原位外延生长石墨烯；实现外延碳化硅-石墨烯的连续生长,从而减少氢气刻蚀带来的晶格缺陷和表面硅富集严重削减现象,并使低成本制备碳化硅上的石墨烯成为可能，并分析探讨了石墨烯气体解吸附特性与解吸附方法；通过实验分析石墨烯对NO2 气体分子的响应时间、气体分子解吸附时间，分析探讨石墨烯的气敏特性；石墨烯对NO2 气体传感灵敏度高，响应快但恢复过程缓慢，气体解吸附时间长；验证了石墨烯对气体具有较好的吸附作用,石墨烯作为气敏材料用于气体传感器是未来的发展趋势。