Study on MBE technologies and optical properties of novel optical functional GeC/Si thin -epitaxial films and nanocrystal assemblies.

为了开发与硅兼容的发光或量子信息器件，我们开发了新的纳米技术，分别通过融合独特的自下而上和自上而下的纳米技术，如分子束外延、固相外延或离子注入方法，在Si(100)衬底上精确地形成了GeC、β-FeSi2或Si的二维纳米晶体(NC)组装。对其NC组装的微观结构和光学性能进行了评价。本课题的主要研究成果如下：(1)对于熔融纳米技术，利用蛋白质铁蛋白的自组装生物纳米工艺，在Si(100)晶片上制备了具有2D组装通孔直径7±2 nm的超薄(~2 nm厚)Si薄膜的新型纳米掩模。它被成功地用于传统的分子束外延、固相外延和低能离子注入技术。(2)通过在Si(100)衬底上非常小且几乎是2D有序的Si纳米掩模通孔，实现了非常小尺寸的二维ASS…用电弧等离子体枪作为C分子束源，用固体源分子束外延生长了更多的晶化Ge_x；1-x；C_x纳米碳管。分子束外延生长的Ge1&t；-x&gt；Cx纳米碳管的替代C含量可达3.2%。在7K的光致发光(PL)谱中，由于量子限制效应，在1.3μm附近出现了一个发光峰。(3)采用极低能量的Si~(++)离子注入(低至0.6keV)和脉冲激光连续退火的方法，在SiO_2薄膜中制备了二维Si-NC组件。结果表明，通过对Si纳米掩模图形的转录，可以得到尺寸非常小且均匀(3.0±0.3 nm)、颗粒间间隔(5~6 nm)的几乎有序的Si-NC组装。在0.6keV注入的Si-β纳米管的荧光光谱的峰值为2lleV，半高宽为78 nm。(4)采用镶嵌固相外延和生物纳米工艺在Si衬底上形成了尺寸很小、密度很高的FeSi2纳米结构，其中含有直径为7 nm的铁蛋白。将β-FeSi2纳米碳包埋在非晶硅薄膜中，在500800℃的超高真空室中用固相外延生长1h。所制备的β-FeSi2纳米结构为二维有序结构，平均直径为6.3±0.3 nm，密度为6.2×10^(11)点/cm2，荧光光谱的峰值为0.91 eV

As an aim at Si-compatible light emitting or quantum information devices, we have developed new nanotechnologies of forming precisely 2-D nano-crystal (NC) assemblies of GeC, β-FeSi_2 or Si on Si (100) substrates by fusing unique bottom-up-type and top-down-type nanotechnologies such as molecular beam epitaxy (MBE), solid phase epitaxy (SPE) or ion-implantation method, respectively. The microscopic structural and optical properties of their NC assemblies were evaluated. The brief results of this research project are as follows;(1) For the fused nanotechnology, a novel 'nanomask' of an ultra-thin (〜2 nm thick) Si film with 2D-assembled via-holes 7±2 nm in diameter on a Si (100) wafer was developed by means of a self-assembled bio-nanoprocess using proteins 'ferritin'. It was used successfully for conventional MBE, SPE and low-energy ion-implantation techniques.(2) Through very small and almost 2D-ordered via-holes of the Si nanomask on the Si (100) substrate, very small-size and 2-D ass … More embled Ge_<1-x>C_x NCs were grown by solid-source MBE with an arc-plasma gun as a C molecular beam source. The MBE-grown Ge1_<-x>Cx NCs were obtained up to a substitutional C content of x=3.2%. In the photoluminescence (PL) spectra at 7K, a PL peak appeared around 1.3 μm due to the quantum confinement effect. We could not make clear the origin of the extremely large band bowing so far.(3) 2-D Si-NC assemblies in SiO_2 thin films were synthesized by using very-low-energy Si^+ ion-implantation (down to 0.6keV) and sequential annealing with a Nd:YAG pulsed laser. As a result, almost ordered Si-NC assemblies with very small and uniform size (3.0±0.3 nm in diameter) and inter-particle separation (5 to 6 nm) were obtained by the transcription of the Si nanomask pattern. The PL spectra of Si-NCs implanted at 0.6keV were observed with a peak of 2lleV and an FWHM of 78 nm.(4) Very smallsize and high-density β-FeSi_2 NC assemblies were formed on a Si (100) substrate using an embedded solid-phase epitaxy (SPE) and bio-nanoprocess with proteins 'ferritin' containing Fe_2O_3 cores 7 nm in diameter. The β-FeSi_2 NCs were grown by SPE at 500-800℃ for 1 hr in an ultra-high vacuum chamber after embedded in an amorphous Si thin film. The β-FeSi_2 NC assemblies were almost 2D-ordered with a uniform diameter 6.3±0.3 nm and a density 6.2×10^ (11) dots/cm^2, and their PL spectra with a peak 0.91 eV were obtained Less