基于二维石墨烯缓冲层的Si(100)衬底单晶GaN材料生长研究

Because of the large bandgap, high electron saturation drift speed, strong breakdown electric field and antiradiation properties, GaN-based materials are widely used in optoelectronics and microelectronic devices. Epitaxial growth of GaN on Si benefits from the low-cost and large-size of Si substrate and will also promote integration of GaN-based devices with Si-based devices. However, due to the surface reconstruction of Si(100), GaN on Si(100) resulted in island morphology with two twisted domains. In this project, amorphous SiO2 will be used to screen the effect from the two kinds of dangling bonds on Si(100) surface. Then, graphene will be transferred onto Si(100)/SiO2 substrate to serve as the required hexagonal template for epitaxy of GaN. Aiming to grow single crystal GaN film on Si(100) substrate, the key physical scientific questions will be investigated, i.e. the effect of surface pretreatment on the surface reactivity and dangling bonds on graphene, adsorption mechanism of atomson graphene ; growth kinetics of GaN and nucleation mechanism of nitride on Si(100)/SiO2/graphene. This work will pave the way for the integration of GaN-based devices and Si-based devices.

GaN基半导体材料由于禁带宽度大、电子饱和漂移速度高、击穿电场强、抗辐照等特点广泛应用于光电子和微电子器件。Si衬底外延生长GaN为GaN基器件制备提供了一种低成本大尺寸的解决方法，同时Si(100)衬底外延GaN为推动GaN基器件和Si基器件集成提供了巨大优势。但是由于Si(100)表面重构产生两种悬挂键，导致氮化物生长时晶粒面内取向不一致，使得Si(100)衬底外延GaN很难发展。本项目提出在Si(100)衬底上生长非晶SiO2以有效屏蔽衬底表面的两种悬挂键信息，并将石墨烯转移至SiO2上以提供氮化物外延生长所需的六方模板，通过系统研究表面预处理对石墨烯表面反应活性及悬挂键的作用规律、石墨烯表面原子吸附机理、GaN生长动力学和氮化物的成核机理，在Si(100)衬底上生长GaN单晶薄膜，为GaN基器件与Si基器件的集成奠定良好基础。

Si(100)衬底外延GaN，不仅具有Si衬底材料的大尺寸低成本优势，而且在GaN基器件与Si基器件的整合集成方面拥有巨大应用前景。但是由于Si(100)表面重构，导致Si(100)上GaN为双畴多晶结构。为解决上述问题，本项目采用SiO2/转移单晶石墨烯为插入层，以实现Si(100)上高质量GaN单晶薄膜为目标展开研究，取得的主要研究成果有：(1) 掌握了石墨烯表面功能化的可控修饰规律，从而实现了石墨烯上氮化物的高密度有效成核并揭示了其成核机理；(2) 在此基础上，通过优化GaN生长工艺，在Si(100)衬底上实现了高质量GaN单晶薄膜的生长；(3) 探索揭示了二维石墨烯作为外延模板生长单晶氮化物的外延机理。本项目研究成果为GaN基器件与Si基器件的整合集成奠定了基础，主要研究结论可应用于在其他二维材料上外延生长氮化物。