离子束共溅射SiGe纳米岛的演变行为及二次生长机制研究

发布时间：2018-01-16 14:39

本文关键词：离子束共溅射SiGe纳米岛的演变行为及二次生长机制研究　出处：《云南大学》2015年硕士论文　论文类型：学位论文

【摘要】：半导体纳米岛(Ge、InAs)由于具有三维限制效应、库伦阻塞效应、声子瓶颈效应等独特的性质在高效光电子与微电子器件领域有着非常重要的应用。对于IV族半导体材料,在Si基衬底上通过Stranski-Krastanov(S-K)模式自组装生长的SiGe纳米岛由于可直接与传统成熟的硅基CMOS读出电路集成的优势使得其具有较大的研究意义,目前已成为学术研究的热点之一。研究微晶硅(μc-Si)上SiGe纳米岛的共溅射生长有助于了解不同结晶性Si缓冲层上SiGe纳米岛的生长演变机制,同时μc-Si材料与红外Ge材料的结合有助于新型微晶器件的开发。原子力显微镜(AFM)测试结果表明：在700℃时,共溅射的SiGe纳米岛呈现双模分布,75%的纳米岛为短岛(h3nm),25%的纳米岛为高岛(3h6nm)。在750℃时,共溅射的SiGe纳米岛呈现多模分布,纳米岛的尺寸变大,均匀性有所提高。Raman光谱图显示：在700℃时,Si缓冲层呈现微晶态,峰位位于381cm-1的振动峰来自于覆盖在μc-Si缓冲层的非晶硅(a-Si)区上的非晶硅锗(a-SiGe)的Si-Ge振动峰,而位于395cm-1的振动峰来自于μc-Si缓冲层的结晶硅(c-Si)区上的SiGe纳米岛的Si-Ge振动峰。在750℃时,Si缓冲层呈现结晶态,并未发现来自于a-SiGe的Si-Ge振动峰,由此可见在μc-Si上共溅射SiGe后表面呈现一种混相结构,即包含a-SiGe和SiGe纳米岛两种不同相的材料。在共溅射SiGe层的基础上,我们再在其上溅射不同厚度的Ge层,主要研究μc-Si上SiGe纳米岛的二次生长行为及表面原子的迁移机制,从而为微晶器件的制备提供新的思路。研究表明：二次生长的纳米岛在700℃呈现优先生长模式,即沉积的Ge原子优先在原先共溅射的高岛聚集形成超级岛。另一方面,在二次生长后有一类底宽较窄、高度较高的纳米岛出现,这是基于Ge和Si之间4.2%的晶格失配而形成的新的纳米岛。在730℃时,纳米岛的二次生长呈现Ostwald熟化模式,大部分的纳米岛在沉积Ge后共同生长,呈现粗化趋势,并出现大岛兼并小岛的现象,一部分纳米岛的体积、高宽比缩小。在700℃时,随着Ge沉积量的增加,共溅射SiGe层上的a-SiGe逐渐消失,这是由于a-SiGe中的原子由于表面化学势差和热扩散行为逐渐迁移到纳米岛中,最终形成互混更加严重的SiGe合金纳米岛。而在730℃时,由于不存在a-SiGe,因此其Si-Ge互混机制就是Si原子从Si缓冲层通过热扩散向上迁移到纳米岛中,从而导致纳米岛中的Ge组分下降。在二次生长后,优先生长的超级岛的高宽比比熟化生长的超级岛的高宽比大,这是由于熟化生长的纳米岛Si-Ge互混较为严重,从而导致高宽比较低。另一方面,由于700℃时Si缓冲层为混相状态,a-Si的表面能(1.05±0.14N/m)比Ge的表面能(～0.75N/m)大但是比c-Si的表面能(～1.4N/m)小,在沉积Ge前期,Ge率先在c-Si上成核,随着Ge沉积量的增加,当纳米岛越过结晶区跨越到非晶区时,由于Ge较难在a-Si上浸润,因此纳米岛在横向方向上的生长受到了限制,使得纳米岛的高宽比有所提高。
[Abstract]:The semiconductor nano island (Ge, InAs) with three-dimensional confinement effect, Kulun blocking effect, the unique nature of the phonon bottleneck effect has a very important application in the field of optoelectronic and microelectronic devices. For efficient IV semiconductor material in Si substrate by Stranski-Krastanov (S-K) model of the self-assembled growth of nano island due to SiGe can be directly with the traditional mature silicon CMOS readout integrated circuit which has the advantages of larger significance, has become one of the hot topic in academic research.
Study on microcrystalline silicon (c-Si) on SiGe co sputtering nano island growth helps to understand the different crystallization of Si buffer layer on SiGe nano island growth evolution mechanism, combined with c-Si materials and infrared Ge materials can help development of new ceramic devices. Atomic force microscopy (AFM) test results showed that: at 700 DEG C, SiGe nano island co sputtering showed bimodal distribution, 75% nano island short Island (h3nm), 25% nano island High Island (3h6nm). At 750 DEG C, SiGe nano island co sputtering showed multimodal distribution, nano island size, uniformity increased.Raman the spectra showed that at 700 DEG C, Si buffer layer showed a micro crystalline, vibration peak position at 381cm-1 from the cover of amorphous silicon in the c-Si buffer layer (a-Si) amorphous silicon germanium (a-SiGe) on the Si-Ge vibration peaks, and vibration peaks in 395cm-1 from the c-Si buffer the crystalline silicon layer (c-Si) Si-Ge vibration peaks of SiGe nano island on. At 750 DEG C, Si buffer layer is crystalline, did not find the Si-Ge vibration peaks from a-SiGe, thus it can be seen in the c-Si on the SiGe surface after CO sputtering showed a mixed phase structure, which includes a-SiGe and SiGe nano island two different phase materials.
Based on the co sputtering of SiGe layer, we then in the sputtered Ge layer with different thickness, migration mechanism main research c-Si SiGe nano island two growth behavior and surface atoms, and ceramics fabrication and provide a new way of thinking. The research showed that: two the growth of nano island is preferred the growth pattern of 700 degrees, which deposited Ge atoms preferentially in the high island was originally co sputtering together to form a super island. On the other hand, in the two growth after a bottom width is narrow, high nano island, which is 4.2% between Ge and Si based on lattice mismatch form the new nano island. At 730 DEG C, two nano island growth and Ostwald ripening model, most of the growth in the co deposition of Ge nano island, showing coarsening trend, and the emergence of big mergers island phenomenon, part of the nano island volume, the ratio of height to width narrowing. At 700 DEG C, with Ge The increase of deposition, a-SiGe co sputtering SiGe layer gradually disappeared, this is because the a-SiGe atoms in the surface of the chemical potential difference and thermal diffusion behavior gradually migrated to the nano island, and ultimately the formation of mixed SiGe alloy nano island is more serious. But at 730 DEG C, since there is no a-SiGe, so the Si-Ge mixed mechanism is Si atoms from the Si buffer layer by thermal diffusion to migrate to the nano island, resulting in Ge group of nano island decreased.
In the two growth after the preferential growth of super super island island wide Bibi high growth of the aging high aspect ratio, which is due to the growth of Si-Ge curing nano island mixed is more serious, which leads to high width is relatively low. On the other hand, due to 700 degrees Si buffer layer is a mixed phase state, a-Si the surface energy of (1.05 + 0.14N/m) than the surface energy of Ge (~ 0.75N/m) but than the surface energy of c-Si (~ 1.4N/m), in the early deposition of Ge, Ge took the lead in c-Si nucleation, with the increase of the Ge deposition, when the nano island across the crystalline region across the amorphous region, due to Ge difficult to infiltrate in a-Si, so nano island in the transverse direction of the growth is limited, the high aspect ratio nano island is improved.

【学位授予单位】：云南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304

【参考文献】