《步天歌》星象——中国传承星象的晚期定型

:《步天歌》属初唐作品 ,主要记载两汉时期以后的星象。由于其主要靠抄本流传 ,且行文过简 ,枝节缺失较多 ,讹误差错不少。但《步天歌》是对隋唐之际传统的三家星官混一的歌诀式总结 ,流传甚广。朝鲜、日本、越南及邻近我国东南沿海国家都有其流传。因此 ,《步天歌》无疑是一部具有较大影响的古代天文星象诗歌著作     

Evaluation of the relative γ-ray intensities emitted from ^56Co and ^66Ga

~(56)Co and ~(66)Ga with γ-ray energies covering the range of 0.84-3.55 and 0.68-4.81MeV, respectively, are important radionuclides for Ge detector calibration. The newly evaluated relative γ-ray intensities were recommended using the measurements finished after 2000 year by Baglin and Browne in 2004. In 2005 China groups measured the relative γ-ray intensities. The China measurements were about 2% systematically lower than other measurements and these evaluations. In this paper the discrepancies among these measurements and the evaluations are analyzed carefully and the new evaluations are re-recommended.     

Surface activation using oxygen and nitrogen radical for Ge-Si Avalanche photodiode integration

In this work, an alternative method for producing the single crystalline Ge-Si Avalanche photodiodes (APD) with low thermal budget was investigated. Structural and electrical investigations show that low temperature Ge to Si wafer bonding can be used to achieve successful APD integration. Based on the surface chemistry of the Ge layer, the buried interfaces were investigated using high resolution transmission electron microscopy as a function of surface activation after low temperature annealing at 200 and 300 °C. The hetero-interface was characterized by measuring forward and reverse currents.     

The effect of Se and Se/Al passivation on the oxidation of Ge

The molecular and atomic oxidation of molecular beam deposited Se passivating layers on Ge substrates was in situ investigated by X-ray photoelectron spectroscopy. It turns out that while Se is efficient in suppressing Ge oxidation upon molecular oxygen exposure, an extra thin Al layer is needed to protect the Ge surface from highly reactive atomic oxygen radicals. Electrical measurements performed on the Al-covered surfaces reveal that Se is beneficial in reducing the interface state density.     

Optimal Growth Conditions for Selective Ge Islands Positioning on Pit-Patterned Si(001)

We investigate ordered nucleation of Ge islands on pit-patterned Si(001) using an original hybrid Kinetic Monte Carlo model. The method allows us to explore long time-scale evolution while using large simulation cells. We analyze the possibility to achieve selective nucleation and island homogeneity as a function of the various parameters (flux, temperature, pit period) able to influence the growth process. The presence of an optimal condition where the atomic diffusivity is sufficient to guarantee nucleation only within pits, but not so large to induce significant Ostwald ripening, is clearly demonstrated.     

Behavior of strain at a thin Ge pile-up layer formed by dry oxidation of a Si0.7Ge0.3 film

The change of strain in Si_0.7Ge_0.3 films was investigated with medium energy ion scattering (MEIS). Si was removed in the films by selective oxidation at 800 °C, resulting in the formation of a Ge pile-up layer on the surface. The relaxation and the thickness of the pile-up layer were closely related to the oxidation time. MEIS data demonstrated that relaxation of the Ge layer in the depth direction occurred partially, and that the rates of relaxation decreased with depth. In addition, the rate of relaxation increased with the oxidation time. Lastly, the relaxation of the Ge layer affected the strain of the remaining Si_0.7Ge_0.3 substrate.     

《抱朴子内篇》的仙论体系

在魏晋南北朝时期,道教神学理论进入了繁忙建设阶段。葛洪作为道教神学理论的奠基人,《抱朴子内篇》是其经典作品。在通过对神仙的有无,成仙的途径手段两个方面作出了创造性的阐述,从而在确立了神仙必有、长生可致的完整体系。     

High-efficiency InGaP/In0.01Ga0.99As tandem solar cells lattice-matched to Ge substrates

Conversion efficiency (AM1.5G) of more than 30% was achieved by adding a small quantity of Indium into a GaAs bottom cell in the conventional tandem solar cell on Ge substrate. It was found that the lattice-mismatch between GaAs and Ge caused misfit-dislocations in thick GaAs layers and reduced an open-circuit voltage (V_oc) of the cell. An In_0.49Ga_0.51P/In_0.01Ga_0.99As tandem cell lattice-matched to Ge showed a great improvement in efficiency, which was attributed to an increase in the V_oc of the bottom cell and increases in the photocurrents both in the top and bottom cells due to reductions in band-gap energy.     

Strain evolution of SiGe-on-insulator fabricated by germanium condensation method with over-oxidation

Strain evolutions of SiGe film during Ge condensation processes of SiGe on silicon-on-insulator were studied in detail with assistance of X-ray diffraction. At the beginning of Ge condensation, SiGe on silicon-on-insulator with low Ge fraction was oxidized at higher temperature of 1150 °C, the strong plastic deformation of buried SiO₂ and Si-Ge intermixing relieved most of the strain in SiGe with increasing Ge fraction. When temperature was reduced to 900 °C for oxidation of SiGe layer with higher Ge fraction, Ge accumulation overmatched Si-Ge inter-diffusion, resulting in non-uniform profile of Ge in SiGe layer. During this period, plastic deformation of buried SiO₂ can be neglected and dislocation gliding plays a significant role in relieving strain in SiGe, which enlarges the surface roughness. The strain in SiGe increases gradually with condensation time for the thickness of SiGe layer reduces close to its critical thickness, even with higher Ge fraction. Intensive over-oxidation of germanium-on-insulator materials was suggested to be effective to fully relax the compressive strain but should be precisely controlled to avoid surface deterioration.     

The n-type Ge photodetectors with gold nanoparticles deposited to enhance the responsivity

Gold nanoparticles (AuNPs) have been deposited on n-type Ge photodetectors to improve the responsivity. Two different coverage ratios, including 10.5 and 30.3% of AuNPs have been prepared, and the fabricated photodetectors are compared with the control sample. The 1,310-nm responsivities at -2 V of the control, 10.5% AuNPs, and 30.3% AuNPs samples are 465, 556, and 623 mA/W, respectively. The AuNPs could increase the responsivities due to the plasmon resonance. The reflectance spectra of these samples have been measured to verify that plasmon resonance contributes to the forward scattering of incident light. The reflectance decreases with AuNP deposition, and a denser coverage results in a smaller reflectance. The smaller reflectance indicates more light could penetrate into the Ge active layer, and it results in a larger responsivity.