Atomic-Layr-Epitaxy of Group VI Semiconductors Using Ultra-Activ Gas

第六族半导体的原子层外延(ALE)利用自然界中不存在的原子氢进行了研究。这种原子氢是由炽热的钨丝的催化效应产生的。在600℃左右交替曝光氢原子和二氢硅烷(SiH_2CI_2)，获得了接近理想的单层/周期生长速率。利用俄歇电子能谱(AES)和X射线光电子能谱(XPS)对Ge衬底上外延层界面的成分变化进行了研究，发现从第一个周期开始，Si膜是逐层生长的，但表面总是被低表面能的Ge单层覆盖。还证实了Ge的ALE可以通过改变Ge_2(C_2H_5)_2的源来获得，尽管不能获得理想的生长速率。这可能是由于在300℃左右的低温下残留在表面的氢原子所致，因此我们将源气改为GeH_2(CH_3)_2，并在500℃左右成功地获得了理想的单层生长速率。我们还尝试了Ge在Si上的异质生长，但发现表面有大量的C原子，但有少量的Ge。因此，我们得出结论，通用电气的第一个异质市场应该发明新的技术。

Atomic Layr Epitaxy (ALE) of group VI semiconductors has studied using atomic hydrogen, which does not exist in nature. This atomic hydrogen has been generated by Catalithic effects of hot tungsten filament. By alternative exposure of atomic hydrogen and dichrolo-silane (SiH2CI2), nearly ideal growth rate of 1 monolayr per cycle has been achieved at temperatures around 600C.This ALE cycle has been applied to Ge substrate to evaluate a compositional change at the interface between the epitaxial layr, by using AES and XPS.It was found that Si film is grown in layr-by-layr manner from the first cycle, but that the surface is always covered by Ge monolayr having low surface energy.It was confirmed also that ALE of Ge is possible by changes source to GeH2(C2H5) 2 although the ideal growth rate can not be obtained. This seems to be caused by residing hydrogen atoms at the surface due to low ALE temperature of about 300C.Thus we have changed the source gas to GeH2(CH3) 2 and succeeded to obtain the ideal monolayr growth rate at about 500C.We have also tried the hetero ALE of Ge on Si, but found that there are a lot of C atoms at the surface but a few Ge. Thus we concluded that novel technology should be invented for the first hetero-ALE layr of Ge.