Low‐temperature atomic layer deposition of MoOx for silicon heterojunction solar cells

The preparation of high‐quality molybdenum oxide (MoO_x) is demonstrated by plasma‐enhanced atomic layer deposition (ALD) at substrate temperatures down to 50 °C. The films are amorphous, slightly substoichiometric with respect to MoO₃, and free of other elements apart from hydrogen (&11 at%). The films have a high transparency in the visible region and their compatibility with a‐Si:H passivation schemes is demonstrated. It is discussed that these aspects, in conjunction with the low processing temperature and the ability to deposit very thin conformal films, make this ALD process promising for the future application of MoO_x in hole‐selective contacts for silicon heterojunction solar cells. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Local friction at a sliding interface between an elastomer and a rigid spherical probe

This paper reports on spatially resolved measurements of the shear stress distribution at a frictional interface between a flat rubber substrate and a glass lens. Silicone rubber specimens marked close to their surface by a colored pattern have been prepared in order to measure the surface displacement field induced by the steady-state friction of the spherical probe. The deconvolution of this displacement field then provides the actual shear stress distribution at the contact interface. When a smooth glass lens is used, a nearly constant shear stress is achieved within the contact. On the other hand, a bell-shaped shear stress distribution is obtained with rough lenses. These first results suggest that simple notions of real contact area and constant interface shear stress cannot account for the observed changes in local friction when roughness is varied.     

Electrical metal contacts to atomically thin 2H-phase MoTe2 grown by metal–organic chemical vapor deposition

We grow atomically thin molybdenum ditelluride (MoTe₂) films on a SiO₂/Si substrate by means of metal–organic chemical vapor deposition (MOCVD). Our Raman spectroscopy measurements reveal the formation of 2H-phase MoTe₂ films. Further, transmission electron microscopy and X-ray photoelectron spectroscopy studies indicate a three-atomic-layer structure and the surface element composition of MoTe₂ films. In this study, we mainly focus on the influence of metal contacts attached to the films on their electrical performance. We fabricate 2H-phase-MoTe₂-based field-effect transistors (FETs) with various metal contacts such as titanium/gold, nickel and palladium, which present p-type semiconductor properties. We also examine the influence of the work functions of the contact metals on the electrical properties of three-atomic-layer-MoTe₂-based FET devices. For a p-type MoTe₂ semiconductor, higher work functions of the contact metals afford narrower Schottky barrier heights (SBHs) and eventually highly efficient carrier injection through the contacts.     

Application of mean‐separation‐works method to protein crystal nucleation

Using mean‐separation‐works method of Stranski and Kaischew calculations of nucleus form and energy barrier for its formation are performed for globular protein crystals. This is done on the basis of a simple model suggested for crystal nucleation of such proteins. The prerequisite for the model is the fact that strict selection of definite sticky patches on protein molecule surface is obligatory for forming crystal lattices. The calculation results are in agreement with experimental data. (© 2008 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

高光束质量垂直腔面发射激光器同相耦合阵列

质子注入型面发射激光器相干耦合阵列能够实现同相模式的激射,但是由于制作过程中的工艺不均匀性引起单元间存在相位差,影响光束的质量。本文通过设计分离电极结构,使每个单元注入的电流得到分别的控制,实现了3单元三角排列阵列高光束质量同相耦合模式的激射。阵列远场发散角仅为3.4°,大约有25.6%的全部能量聚集在中心光斑。激射光谱的线宽为0.24 nm,边模抑制比为27 dB。该方法能够有效提高相干耦合阵列的光束质量,弥补制作工艺中引入的单元不均匀性,提高器件的可靠性和实用性。质子注入方法简单、成本低,能够成为制作高光束质量相干耦合阵列的一个重要方法。     

Homogenization with the Quasistatic Tresca Friction Law:Qualitative and Quantitative Results

Modeling of frictional contacts is crucial for investigating mechanical performances of composite materials under varying service environments.The paper considers a linear elasticity system with strongly heterogeneous coefficients and quasistatic Tresca friction law,and studies the homogenization theories under the frameworks of H-convergence and small ε-periodicity.The qualitative result is based on H-convergence,which shows the original oscillating solutions will converge weakly to the homogen...