Development of multicomponent bulk single crystal with uniform composition by the multicomponent zone-melting method

在这个项目中，我们试图建立一种技术来生长具有均匀组成的多组分半导体块晶体，这有望通过大大拓宽半导体衬底的晶格常数和带隙的选择来产生新的功能异质结构。1999财政年度，我们设计了一套新的生长系统，配备了生长界面位置和温度的原位监测系统。该系统包括一个石英狭缝，它允许一个光学访问，和一个CCD相机观察界面的位置，和一个热观察器，以获得温度分布。此外，该信息还可用于控制晶体生长的坩埚的提拉速率。SiGe块晶体的起始材料是作为源的Si单晶、多晶Ge和Ge（100）单晶。 关于我们 像种子一样说话。通过将锗置于适当的温度梯度中，熔化多晶Ge和Ge单晶的顶部以制备生长熔体。然后，Si溶解到Ge熔体中，并且Si原子主要通过源自浓度梯度的扩散以及可能的对流影响被带到界面。通过对生长过程中界面位置的监测，得到了SiGe晶体生长的速率。通过拉低与生长速率相平衡的SiGe，我们成功地生长了具有固定界面位置的SiGe。经确认，拉下散热器不会影响温度分布。换句话说，SiGe在固定的生长温度下生长。事实上，EDX分析表明，晶体的成分在20 mm以上是均匀的。下一步，我们将把这项技术应用于各种材料系统，并在我们原来的衬底上进行外延生长，以创建新的功能异质结构。少

In this project, we have tried to establish a technology to grow multicomponent semiconductor bulk crystals with uniform composition, which are expected to lead to the creation of new functional heterostructures by greatly widening the choices of lattice constant and band gap of semiconductor substrates. By utilizing the technology, we have grown SiGe bulk crystals.In Fy1999, we designed new growth system equipped with an in-situ monitoring system of the position and the temperature at the growth interface. The system includes a quartz slit which allows an optical access, and a CCD camera to observe the position of the interface, and a thermoviewer to obtain the temperature distribution. In addition, the information can be used to control the pulling rate of the ampoule for the crystal growth. Therefore, precise control of the growth temperature is possible.The starting materials for the SiGe bulk crystal are a Si single crystal as a source, polycrystalline Ge, and Ge (100) single crys … More tal as a seed. By putting the ampoule in an appropriate temperature gradient, polycrystalline Ge and a top part of Ge single crystal are melted to prepare a growth melt. Then, Si dissolves into Ge melt and Si atoms are carried to the interface, mainly by diffusion originating from the concentration gradient, and also by possible influence of convection. Consequently, the supercooling is formed around the growth interface and a driving force for the growth of SiGe crystal is established.By monitoring the interface position during the growth with fixed ampoule, we obtained the growth rate of the crystal. By pulling down the ampoule balanced with the growth rate, we succeeded in growing SiGe with fixed interface position. The pulling down the ampoule was confirmed not to affect the temperature distribution. In other words, SiGe was grown under fixed growth temperature. In fact, EDX analysis clarified that the composition of the crystal is uniform over 20mm.As a next step, we will apply this technique to various material system, and perform epitaxial growth on our original substrates to create new functional heterostructures. Less