有序合金中FCC→HCP相变温度内出现的缺陷

利用ＴＥＭ的高温台原位观察了Ｆｅ３Ｇｅ的相在７８０℃（在７００℃以上Ｌ１２转变为ＤＯ１９）出现缺陷的过程。实验发现首先形核的是外禀层错,外禀层错比孤立的内禀层比孤立的内禀层错扩展得快,并且扩展得较宽,它们有可能长大成为ＤＯ１９相的核胚。     

The GENIUS-test-facility—first results on background from Rn daughters

GENIUS-TF (Nucl. Instr. and Meth. A 511 (2003) 341; Nucl. Instr. and Meth. A 481 (2002) 149.) is a test-facility for the GENIUS project (GENIUS-Proposal, 20 November 1997; Z. Phys. A 359 (1997) 351; CERN Courier, November 1997, 16; J. Phys. G 24 (1998) 483; Z. Phys. A 359 (1997) 361; in: H.V. Klapdor-Kleingrothaus, H. Pas. (Eds.), First International Conference on Particle Physics Beyond the Standard Model, Castle Ringberg, Germany, 8–14 June 1997, IOP Bristol (1998) 485 and in Int. J. Mod. Phys. A 13 (1998) 3953; in: H.V. Klapdor-Kleingrothaus, I.V. Krivosheina (Eds.), Proceedings of the Second International Conference on Particle Physics Beyond the Standard Model BEYOND’ 99, Castle Ringberg, Germany 6–12 June 1999, IOP Bristol (2000) 915), a proposed large scale underground observatory for rare events which is based on operation of naked germanium detectors in liquid nitrogen for an extreme background reduction. Operation of naked Ge crystals in liquid nitrogen has been applied routinely already for more than 20 years by the CANBERRA Company for technical functions tests (CANBERRA Company, private communication, 5 March 2004.), but it never had found entrance into basic research. Only in 1997 first tests of application of this method for nuclear spectroscopy have been performed, successfully, in Heidelberg (Klapdor-Kleingrothaus et al., 1997, 1998; J. Hellmig and H.V. Klapdor-Kleingrothaus, 1997).

On May 5, 2003 the first four naked high-purity germanium detectors (total mass 10.52 kg) were installed in liquid nitrogen in the GENIUS Test Facility at the Gran Sasso underground laboratory. Since then the experiment has been running continuously, testing for the first time the novel technique in an underground laboratory and for a long-lasting period.

In this work, we present the first analysis of the GENIUS-TF background after the completion of the external shielding, which took place in December 2003. We focus especially on the background coming from ²²²Rn daughters. This is found to be at present by a factor of 200 higher than expected from simulation. It is still compatible with the scientific goal of GENIUS-TF, namely to search for cold dark matter by the modulation signal, but on the present level would cause serious problems for a full GENIUS—like experiment using liquid nitrogen.     

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.     

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.     

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。     

Ge(Li)γ谱本底的直接扣除法

本文介绍了一种直接扣除峰下本底的技术,这个技术已在《SPAN Ge(Li)γ谱分析程序》中得到成功的应用。这个方法是积分峰本底技术的完善和发展,它对于十分复杂的包含有多重峰的Ge(Li)γ谱也能得出合理的本底线,并且能从γ谱中直接扣除。     

Catalytic hydrogenation for improvement of GaAs/Ge solar cell efficiency

Hydrogen passivation on MOCVD grown p-GaAs epilayers on Ge substrate have been studied by plasma and catalytic hydrogenation and the results were compared. The conversion efficiency of the GaAs/Ge solar cells was found to increase by 10% after catalytic hydrogenation at AM1.5. This increase in efficiency is probably due to passivation of surface dangling bonds.     

超薄体MOSFET的结构优化

对UTB器件的各结构参数进行了优化,给出了UTB器件设计的指导方向.在UTB器件的设计中,有三个重要参数,即器件的源漏提升高度、锗硅栅(GexSi1-x)中Ge含量的摩尔百分比和硅膜的厚度,并对这三个结构参数对器件性能的影响进行了模拟分析,给出了器件各结构参数的优化方向,找出了可行Ge含量的摩尔百分比和可行硅膜厚度之间的设计容区.通过模拟分析发现,只要合理选择器件的结构参数,就能得到性能优良的UTB器件.