High-quality Si thin film growth on single-crystalline Al203 films

硅上绝缘层的异质外延生长和单晶硅在这些绝缘层上的连续生长对绝缘体上硅(SOI)结构的形成具有重要意义。我们提出了用γ-Al_2O_3薄膜作为绝缘材料，并在伽马-Al_2O_3硅衬底上获得了高质量的薄膜。外延生长的Si/Al_2O_3/Si叠层结构不仅具有蓝宝石上硅(SOS)的特性，而且对于采用微机械加工技术的传感器具有其他优点。然而，对于Si/y-Al_2O_3/Si叠层结构的器件应用来说，必须提高薄膜的结晶质量和表面平整度。在这项研究中，我们报道了在气体源MBE外延生长Si膜之前，在室温下用薄Al层在γ-Al_2O_3/Si(111)衬底上外延生长高晶体质量的Si膜。在Si的外延生长之前，Al以…的速率从努森电池中蒸发在室温下，在γ-Al_2O_3(111)/Si衬底上获得了1a^ﾟ/s以上的热释光。Al薄膜是在室温下外延生长的。采用Al固体源和N_2O气体分子束外延技术，在生长温度为650℃、900ﾟC的Si(111)衬底上外延生长了高结晶质量的γ-Al_2O_3薄膜。将衬底暴露在硅氢化硅的液晶显示器中。硅膜的生长速率为400A·ﾟ/min。在Si_2H_6气态源分子束外延生长Si膜之前，采用在Al_2O_3(111)/Si(111)衬底上沉积薄Al层的方法，在室温下生长出了结晶度较高的非常平坦的Si(111)外延膜。与没有Al预沉积层的外延Si相比，外延Si的晶体质量和表面形貌都有了显著的改善。对于Al厚度为10A^ﾟ的高质量Si薄膜，在800ﾟC生长Si之前，Al沉积表面转变为Al-O表面(而不是金属Al层)，但对于25A^ﾟ厚的Al预沉积层，Al-Al键仍然存在。认为Al_2O_3表面发生了修饰，从而改善了在Al_2O_3上生长的硅膜的结晶质量。

Heteroepitaxial growth of insulating layrs on Si and the successive growth of a single crystalline Si on those insulating layrs are of great interest in the formation of silicon-on-insulator (SOI) structures. We have proposed gamma-Al_2O_3 films as an insulator material and obtained high quality on layrs of gamma-Al_2O_3 Si substrates. Epitaxially grown Si/Al_2O_3/Si stacked structures have not only the features of silicon-on-sapphire (SOS) but also other advantages for sensor devices using micro machining technology. However, for device applications of the Si/y-Al_2O_3/Si stacked structure, it is necessary to improve the crystalline quality and surface flatness of grown films. In this research, we report the high crystalline quality epitaxial growth of Si films using thin Al layr deposited onto gamma-Al_2O_3 (111) /Si (111) substrates at room temperature, prior to the growth of Si films by gas source MBE.Before the epitaxial growth of Si, Al was evaporated from Knudsen cell at a rate … More of 1A^^ﾟ/sec on the gamma-Al_2O_3 (111) /Si substrate at room temperature. The Al films were grown epitaxially at room temperature. High crystalline quality gamma-Al_2O_3 films were epitaxially grown on Si (111) substrates at growth temperatures from 650 at 900ﾟC by Al solid source and N_2O gas molecular beam epitaxy. The substrates were exposed to a Si_2H_6 flow of lsccm. The grown rate of Si films was 400A^^ﾟ/min. Very flat epitaxial Si (111) films with high crystalline quality were grown using thin Al layrs deposited onto Al_2O_3 (111) /Si (111) substrates at room temperature, prior to the growth of Si films by Si_2H_6 gas source molecular beam epitaxy. The epitaxial Si had a significantly improved crystalline quality and surface morphology comparable to that grown without the Al predeposition layr. For an Al thickness of 10A^^ﾟ, the optimum Al thickness for a high quality Si film, the Al deposited surface was changed to an Al-O surface (rather than a metallic Al layr) just before Si growth at 800ﾟC.However, Al-Al bonds remain for an 25-A^^ﾟ-thick Al predeposition layr. It is believed that a modification of the Al_2O_3 surface occur, which results in improved crystalline quality of Si films grown on the Al_2O_3. Less