晶化温度与砷压对Ga在GaAs(001)表面扩散限制的研究

Study on the limitation of Ga diffusion on GaAs(001)surface by crystallization temperature and arsenic pressure

采用液滴外延技术在平坦GaAs(001)表面上制备GaAs纳米环结构。利用原子力显微镜对其表面形貌进行表征,发现在As压保护下金属Ga液滴晶化过程中,液滴内Ga原子存在向外迁移和向下刻蚀两种扩散行为,且扩散行为均受到衬底温度和As压力大小的影响。其中As压主要影响Ga原子在表面横向扩散,而衬底温度主要影响Ga原子在纵向刻蚀扩散。根据量子环结构形貌演变趋势分析了圆盘半径ΔR、R_(p)与沉积量的关系,得出形成扩散盘的Ga临界沉积量为10 mL,并总结出采用降温结晶方式制备GaAs同心量子环的工艺方法。

Gallium droplets are grown on GaAs substrate by droplet epitaxy.The samples with different gallium deposits are characterized by AFM and the surface morphology is observed.The results show that gallium atoms in droplets under arsenic pressure can be divided into two kinds of diffusion behaviors:outward diffusion and downward etching.These diffusion behaviors are affected by substrate temperature and arsenic pressure.The results show that arsenic atoms significantly affects the surface diffusion of gallium atoms,and the inner ring depth is mainly affected by the substrate temperature.The GaAs concentric quantum rings are prepared by cooling crystallization method.The relationship between the disk radiusΔR(R_(p))and the deposition amount is analyzed.The critical deposition amount of GaAs to form the diffusion disk is found to be 10 mL.