硅基高质量氧化锌外延薄膜的界面控制

Interface control for epitaxial growth of high-quality ZnO(0001) film on Si(111) substrate

本文利用反射式高能电子衍射(RHEED)、高分辨透射电镜和选区电子衍射方法,系统研究了Si(111)衬底上制备高质量氧化锌单晶薄膜的界面控制工艺。发现低温下Mg(0001)/Si(111)界面互扩散得到有效抑制,形成了高质量的单晶镁膜,进一步通过低温氧化法和分子束外延法实现了单晶MgO缓冲层的制备,从而为ZnO的外延生长提供了模板。在这一低温界面控制工艺中,Mg膜有效防止了Si表面的氧化,而MgO膜不仅为ZnO的成核与生长提供了优良的缓冲层,且极大地弛豫了由于衬底与ZnO之间的晶格失配所引起的应变。上述低温工艺也可用来控制其它活性金属膜与硅的界面,从而在硅衬底上获得高质量的氧化物模板。

We report on the interface control process for the growth of high-quality ZnO （0001） film on Si （111 ） substrate. By using in situ reflective high-energy electron diffraction combined with ex situ high-resolution transmission electron microscopy and selective area electron diffraction, it was revealed that high-quality Mg film can be obtained on Si（ 111 ）-7× 7 at low temperature （0℃） in which the mutual diffusion of Mg and Si had been completely suppressed. Then, a well-defined MgO layer was formed by the oxidation of the Mg film and MgO homoepitaxy at low temperature. The high-quality Mg film effectively protected Si from oxidation. Meanwhile, the MgO layer not only provided an excellent template for the nuclei of ZnO, but also greatly relieved the residual strain in the ZnO film caused by the huge lattice mismatch between ZnO and Si. The low-temperature interface control technique can also be applied to control other reactive metal/Si interfaces and obtain high-quality oxide templates accordingly.