基于离子束辅助沉积生长柔性类单晶硅的方法

Method for Growing Flexible Single-Crystal-Like Silicon Based on Ion Beam Assisted Deposition

通过离子束辅助沉积(IBAD)和射频磁控溅射(RFMS)的方法在低成本、柔性且轻质的金属箔基板上异质外延生长类单晶硅薄膜。在整个过程中,类单晶的Ge被用作晶格匹配的缓冲层进行Si的外延生长,其中Ge的基材来源于用IBAD法制备的双轴织构的氧化物过渡层。通过Si_(x)Ge_(1-x)的梯度溅射进行Ge与Si之间的过渡,减少其界面缺陷。生长出的外延硅沿[001]方向高度取向,具有强烈的双轴织构,电子背散射衍射结果显示生长的类单晶硅薄膜具有小角度晶界,并且超过98%的晶粒与晶粒间的取向差小于2°。透射电子显微镜(TEM)的电子衍射图也证实了薄膜的类单晶性质。Raman光谱显示硅薄膜具有高的结晶度,结晶度几乎可与单晶硅片相媲美。与没有Si_(x)Ge_(1-x)缓冲层的Si薄膜相比,具有缓冲层的Si薄膜表现出更好的织构、结晶度和更少的缺陷。在电性能方面,测得的n-Si薄膜掺杂浓度约为5×10^(18)cm^(-3),电子迁移率为110 cm^(2)/(V·s)。因此,采用RFMS和IBAD的方法可以为在柔性和低成本的非晶衬底上直接沉积高电子迁移率半导体薄膜提供一种新思路,这种新思路也为高性能印刷电子、柔性太阳电池和柔性电子应用提供了新的机会。

The ion beam assisted deposition(IBAD)and radio frequency magnetron sputtering(RFMS)methods were used to hetero-epitaxially grow single-crystal-like silicon thin films on the metal foil substrate with low cost,flexibility and light weight.In the whole process,the single-crystal-like Ge was used as a lattice matched buffer layer for Si epitaxial growth,in which the substrate material of Ge was derived from the oxide transition layer with biaxial texture prepared by IBAD method.The transition between Ge and Si was performed by Si_(x)Ge_(1-x) gradient sputtering to reduce interface defects.The grown epitaxial silicon is highly oriented along the[001]direction and has a strong biaxial texture.Electron back scattered diffraction result shows that single-crystal-like Si thin films have a low-angle grain boundary and more than 98% grain-to-grain mis-orientation is less than 2°.The electron diffraction pattern of the transmission electron microscope(TEM)also confirms the single-crystal-like property of the thin film.Raman spectroscopy shows that silicon thin films have high crystallinity,which is almost comparable to monocrystalline silicon wafers.Compared with the silicon thin film without Si_(x)Ge_(1-x) buffer layer,the silicon thin film with buffer layer has better texture,crystallinity and fewer defects.In terms of electrical properties,the measured doping concentration of the n-Si thin film is about 5×10^(18)cm^(-3),and the electron mobility is 110 cm^(2)/(V·s).Therefore,the RFMS and IBAD methods can provide a new idea for direct deposition of high electron mobility semiconductor thin films on flexible and low-cost amorphous substrates,and the new idea also provides a new opportunity for high-performance printed electronics,flexible solar cells and flexible electronic applications.