Issues of morphology, nucleation and growth of Ge cluster arrays deposited by ultrahigh vacuum molecular beam epitaxy on the Si(001) surface are considered. Difference in nucleation of quantum dots during Ge deposition at low (<600 deg C) and high (>600 deg. C) temperatures is studied by high resolution scanning tunneling microscopy. The atomic models of growth of both species of Ge huts---pyramids and wedges---are proposed. The growth cycle of Ge QD arrays at low temperatures is explored. A problem of lowering of the array formation temperature is discussed with the focus on CMOS compatibility of the entire process; a special attention is paid upon approaches to reduction of treatment temperature during the Si(001) surface pre-growth cleaning, which is at once a key and the highest-temperature phase of the Ge/Si(001) quantum dot dense array formation process. The temperature of the Si clean surface preparation, the final high-temperature step of which is, as a rule, carried out directly in the MBE chamber just before the structure deposition, determines the compatibility of formation process of Ge-QD-array based devices with the CMOS manufacturing cycle. Silicon surface hydrogenation at the final stage of its wet chemical etching during the preliminary cleaning is proposed as a possible way of efficient reduction of the Si wafer pre-growth annealing temperature.
Structural and transport properties of highly Ru-deficient SrRu0.7O3 thin films prepared by molecular beam epitaxy: comparison with stoichiometric SrRuO3
Room temperature ferromagnetism of monolayer chromium telluride with perpendicular magnetic anisotropy
在二维(2D)系统中实现长程磁有序化可能会彻底改变下一代信息技术。在这里,我们报告的晶体Cr 3 Te 4单层室温铁磁性的成功制造。采用分子束外延技术,在较低的衬底温度(~ 100 ℃)下生长了单层厚度的二维Cr 3 Te 4薄膜,与Si CMOS工艺兼容。X射线磁性圆二色性测量揭示了具有面外磁易轴的Cr 3 Te 4单层的居里温度(Tc)为~344 K,对于具有面内易轴的较厚的膜(~ 7 nm),居里温度降低到~240 K。通过密度泛函理论计算,将铁磁耦合和磁各向异性转变的增强归因于界面效应,特别是单层Cr 3 Te 4/石墨界面处的轨道重叠.这项工作揭示了具有室温铁磁性的2D非层状材料的低温可扩展生长,用于新的磁性和自旋电子器件。
High-sensitive MIS structures with silicon nanocrystals grown via solid-state dewetting of silicon-on-insulator for solar cell and photodetector applications