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Graphene/Ge/Si heterostructure were fabricated on Si(1 0 0) by direct transfer method. The monolayer graphene was transferred onto Ge/Si epilayer with the Raman intensity ratio (I2D/IG) of 1.75. The defect related D peak located at 1346 cm−1 is also very weak, signified the small amount of defects. Raman spectroscopy confirmed single crystal Ge film with S-K growth mode was obtained. The lattice mismatch between Ge and Si causes 0.8° off axis of Ge film. The growth mode of Ge film also confirmed as S-K mode when the growth temperature is higher than 650 °C, which cause a lower shift of Ge Raman shift peak.

Topography has remarkable effects on the local climate, especially in mountainous areas. The accuracy of climate data is pivotal to the estimation of net primary productivity (NPP). Unrealistic simulations of climate data without considering the topography would lead to biased estimation of NPP. In this work, we aim to evaluate quantitatively the NPP difference with and without considering the topographical effects of climate data, and furthermore, to explore the spatio-temporal characteristics of NPP difference and the primary contributing variables to the difference. For these purposes, two different climate datasets were first built and compared with the station observations, one of which considered topographical effects (terrain-based climate dataset) while the other one did not (ordinary climate dataset). We quantified topographical effects of climate data on NPP estimation by inputting two different climate datasets to the same ecosystem model, the Boreal Ecosystem Productivity Simulator (BEPS), to evaluate the importance of considering topography during NPP calculations. Then, spatio-temporal characteristics of the NPP difference were explored, and the primary contributing variables were determined through a series of simulation experiments. Results showed that, on average, ordinary climate dataset underestimated NPP by 12.5% compared with terrain-based climate dataset over the whole Wuling mountainous area. Topographical effects of climate data had larger impacts on the NPP estimation in summer time than in winter months. In space, differences between ordinary NPP and terrain-based NPP were negligible below 200 m, and above 200 m, the differences increased first and then steadily decreased; discrepancies between NPPs continually augmented with the slope increasing; and NPP was more likely to be affected in the north and northwest than in the south and southeast. The primary climate variables contributing to the NPP difference in Wuling mountainous area were temperatures, followed by global solar radiation. The research methods developed in this case study can also be applied to other study areas and other ecosystem models.

Crystalline SiC samples were prepared in solidification of silicon melt saturated by carbon solved from the inner wall of a graphite crucible. The crystalline structure of the samples was analysed in Raman spectroscopy and confirmed as 3C-SiC both in x-ray diffraction and x-ray photoelectron spectroscopy (XPS). The Raman spectra of the samples present a strong sharp peak located at 796.3 cm-1 with a full width at half maximum about 6 cm-1 and three weak peaks broadened around 1525.6, 1631.4 and 1719.1 cm-1, respectively. The former belongs to the transverse optical phonons of 3C-SiC, while the latter can be attributed to the second-order scattering. However, the longitudinal optical mode of 3C-SiC has not been found for our samples. An additional broadened peak at 532.2 cm-1 may imply the existence of some lattice defect in the samples, which is related to nitrogen introduced unintentionally into the lattice in the growth process and confirmed in XPS of N 1s binding energy centred at 400.9 eV.

Although serious attempts have been developed silicon carbide bulk crystal growth technology to an industrial process during the last years, the quality of crystal remains deficient. One of the major problems is that the thermal field of SiC growth systems is not fully understood. Numerical simulation is considered as an important tool for the investigation of the thermal field distribution inside the growth crucible system involved with SiC bulk growth. We employ the finite-element software package ANSYS to provide additional information on the thermal field distribution. A two-dimensional model has been developed to simulate the axisymmetric growth system consist of a cylindrical susceptor (graphite crucible), a graphite felt insulation, and a copper inductive coil. The modeling field is coupled electromagnetic heating and thermal transfer. The induced magnetic field is used to predict heat generation due to magnetic induction. Conduction, convection and radiation in various components of the system are accounted for the heat transfer ways. The thermal field in SiC sublimation growth system was provided.