当前位置: X-MOL 学术ACS Nano › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Oxide-Free Three-Dimensional Germanium/Silicon Core-Shell Metalattice Made by High-Pressure Confined Chemical Vapor Deposition.
ACS Nano ( IF 15.8 ) Pub Date : 2020-09-17 , DOI: 10.1021/acsnano.0c03559
Pratibha Mahale 1 , Parivash Moradifar 2 , Hiu Yan Cheng 3 , Nabila Nabi Nova 3 , Alex J Grede 4 , Byeongdu Lee 5 , Luis R De Jesús 1 , Maxwell Wetherington 6 , Noel C Giebink 4 , John V Badding 2, 3 , Nasim Alem 2 , Thomas E Mallouk 1
Affiliation  

Metalattices are crystalline arrays of uniform particles in which the period of the crystal is close to some characteristic physical length scale of the material. Here, we explore the synthesis and properties of a germanium metalattice in which the ∼70 nm periodicity of a silica colloidal crystal template is close to the ∼24 nm Bohr exciton radius of the nanocrystalline Ge replica. The problem of Ge surface oxidation can be significant when exploring quantum confinement effects or designing electronically coupled nanostructures because of the high surface area to volume ratio at the nanoscale. To eliminate surface oxidation, we developed a core–shell synthesis in which the Ge metalattice is protected by an oxide-free Si interfacial layer, and we explore its properties by transmission electron microscopy (TEM), Raman spectroscopy, and electron energy loss spectroscopy (EELS). The interstices of a colloidal crystal film grown from 69 nm diameter spherical silica particles were filled with polycrystalline Ge by high-pressure confined chemical vapor deposition (HPcCVD) from GeH4. After the SiO2 template was etched away with aqueous HF, the Ge replica was uniformly coated with an amorphous Si shell by HPcCVD as confirmed by TEM-EDS (energy-dispersive X-ray spectroscopy) and Raman spectroscopy. Formation of the shell prevents oxidation of the Ge core within the detection limit of XPS. The electronic properties of the core–shell structure were studied by accessing the Ge 3d edge onset using STEM-EELS. A blue shift in the edge onset with decreasing size of Ge sites in the metalattices suggests quantum confinement of the Ge core. The degree of quantum confinement of the Ge core depends on the void sizes in the template, which is tunable by using silica particles of varying size. The edge onset also shows a shift to higher energy near the shell in comparison with the Ge core. This shift along with the observation of Ge–Si vibrational modes in the Raman spectrum indicate interdiffusion of Ge and Si. Both the size of the voids in the template and core–shell interdiffusion of Si and Ge can in principle be tuned to modify the electronic properties of the Ge metalattice.

中文翻译:

通过高压密闭化学气相沉积法制得的无氧化物三维锗/硅核壳金属晶格。

金属是均匀颗粒的晶体阵列,其中晶体的周期接近材料的某些特征物理长度尺度。在这里,我们研究了锗金属晶格的合成和性质,其中二氧化硅胶体晶体模板的〜70 nm周期性接近纳米晶Ge复制品的〜24 nm Bohr激子半径。当探索量子约束效应或设计电子耦合的纳米结构时,由于纳米级的高表面积体积比,Ge表面的氧化问题可能非常严重。为了消除表面氧化,我们开发了核-壳合成方法,其中锗金属晶格受到无氧化物的Si界面层的保护,并且我们通过透射电子显微镜(TEM),拉曼光谱,和电子能量损失谱(EELS)。通过来自GeH的高压密闭化学气相沉积(HPcCVD),在直径为69 nm的球形二氧化硅颗粒中生长的胶态晶体膜的空隙中填充了多晶Ge4。SiO 2之后用HF水溶液蚀刻掉模板,如通过TEM-EDS(能量分散X射线光谱法)和拉曼光谱法所证实的,通过HPcCVD将Ge复制品均匀地涂覆有非晶硅壳。壳的形成防止了在XPS的检测极限内Ge核的氧化。通过使用STEM-EELS访问Ge 3d边缘起始点,研究了核-壳结构的电子性质。边缘开始的蓝移随着金属中Ge位点尺寸的减小暗示了Ge核的量子约束。Ge核的量子约束程度取决于模板中的空隙尺寸,这可以通过使用不同尺寸的二氧化硅颗粒来调节。与Ge核相比,边缘开始还显示出壳附近向更高能量的转变。这种移动以及在拉曼光谱中观察到的Ge-Si振动模式表明Ge和Si相互扩散。原则上,可以调整Si和Ge的模板中的空隙大小和核-壳互扩散,以改变Ge金属晶格的电子性质。
更新日期:2020-10-28
down
wechat
bug