利用Al/AlAs中间层调控GaAs在Si(111)上外延生长的研究

为了实现Ⅲ-V器件在硅基平台上单片集成,近年来Ⅲ-V半导体在硅衬底上的异质外延得到了广泛研究。由于Ⅲ-V半导体与Si之间大的晶格失配以及晶格结构不同,在Si上生长的Ⅲ-V半导体中存在较多的失配位错及反相畴,对器件性能造成严重影响。而Si(111)表面的双原子台阶可以避免Ⅲ-V异质外延过程中形成反相畴。本文利用分子束外延技术通过Al/AlAs作为中间层首次在Si(111)衬底上外延生长了GaAs(111)薄膜。通过一系列对比实验验证了Al/AlAs中间层的插入对GaAs薄膜质量的调控作用,并在此基础上通过低温-高温两步法优化了GaAs的生长条件。结果表明Al/AlAs插层可以为GaAs外延生长提供模板,并在一定程度上释放GaAs与Si之间的失配应力,从而使GaAs薄膜的晶体质量得到提高。以上工作为Ⅲ-V半导体在硅上的生长提供了新思路。

Epitaxial Growth of GaAs on Si (111) Controlled by Al/AlAs Interlayer

In order to realize the monolithic integration of Ⅲ-V devices on silicon platform, the heteroepitaxy of Ⅲ-V semiconductor on silicon substrate has been widely studied in recent years. Due to the large lattice mismatch and different lattice structure between Ⅲ-V semiconductor and Si, there are many mismatches and antiphase domains in Ⅲ-V semiconductor grown on Si, which have a serious impact on device performance. However, the diatomic steps on Si (111) surface can avoid the formation of antiphase domains. In this work, GaAs (111) films were grown on Si (111) substrate by molecular beam epitaxy, and Al/AlAs was used as intermediate layer for the first time. A series of samples were grown to optimize the growth conditions of Al/AlAs interlayer and it is shown that Al/AlAs interlayers have positive effect on the quality of subsequent GaAs films. On this basis of the Al/AlAs interlayers, the GaAs films were grown by two-step method and the growth conditions were optimized. The results show that Al/AlAs interlayers provide a template for the epitaxial growth of GaAs and release the mismatch strain between GaAs and Si to a certain extent, so that the crystal quality of GaAs films can be improved. All of the above-mentioned work can provide new ideas and pathways for the growth of Ⅲ-V semiconductor on silicon.