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

硅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γ - al_2o_3薄膜作为绝缘体材料，并在γ - al_2o_3 Si衬底上获得了高质量的绝缘体。外延生长的Si/Al_2O_3/Si堆叠结构不仅具有蓝宝石上硅（SOS）的特性，而且对于采用微加工技术的传感器器件具有其他优点。然而，对于Si/y-Al_2O_3/Si堆叠结构的器件应用，需要提高生长膜的结晶质量和表面平整度。在本研究中，我们报道了在室温下，在γ - al_2o_3 (111) /Si（111）衬底上沉积薄Al层，在气源MBE生长Si薄膜之前，高结晶质量的Si薄膜外延生长。在Si外延生长之前，Al在γ - al_2o_3 (111) /Si衬底上以大于1A^^ /秒的速率在室温下从Knudsen电池中蒸发。铝薄膜在室温下外延生长。采用Al固体源和N_2O气体分子束外延技术，在650 ~ 900℃的温度下，在Si（111）衬底上生长出了高结晶质量的γ - al_2o_3薄膜。底物暴露于lsccm的Si_2H_6流中。Si薄膜的生长速率为400A^^ /min。在采用Si_2H_6气体源分子束外延技术生长Si（111）薄膜之前，先在Al_2O_3 (111) /Si（111）衬底上沉积薄Al层，在室温下生长出具有高结晶质量的非常平坦的Si（111）外延薄膜。与没有Al预沉积层的外延硅相比，外延硅的晶体质量和表面形貌明显改善。当Al的厚度为10A^^（高质量硅膜的最佳Al厚度）时，在800 C下生长之前，Al沉积表面转变为Al- o表面（而不是金属Al层）。然而，在25-A^^厚的Al预沉积层中，Al-Al键仍然存在。认为Al_2O_3表面发生了修饰，从而提高了在Al_2O_3表面生长的Si薄膜的结晶质量。少

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