Combination of Instrumented Nanoindentation and Scanning Probe Microscopy for Adequate Mechanical Surface Testing

The elastic indentation modulus and hardness of standard bulk materials and advanced thin films were deter-mined by using the nanoindentation technique followed by the Oliver- Pharr post-treatment. After measure-ments with different loading/unloading schemes on chemically polished bulk titanium a substantial decrease of both modulus and hardness vs an increasing loading time was found, Then, hard nanostructured TiBN and TiCrBN thin films deposited by magnetron sputtering (using multiphase targets) on substrates of high roughness (sintered hard metal) and low roughness (silicon) were studied. Experimental modulus and hardness characterized by using two different nanoindenter tools were within the limits of standard deviation. However, a strong effect of roughness on the spread of the experimental values was observed and it was found that hard-ness and elastic indentation modulus obeyed a Gaussian distribution. The experimental data were discussed together with scanning probe microscopy (SPM) images of typical imprints taken after the nanoindentation tests and the local topography's strong correlation with the results of nanoindentation was described.     

真空蒸镀红荧烯薄膜及其形貌分析

红荧烯(rubrene)即5,6,11,12-四苯基并四苯,是一种重要的小分子有机半导体材料,可以用以制备红荧烯有机场效应管和太阳能光伏器件。本文首先对传统的热蒸发真空系统进行改造,使之能蒸镀有机薄膜。在一定的蒸发温度下,经过不同蒸镀时间蒸镀红荧烯薄膜,蒸镀时间分别为5,6,7,8 h,获得了具有多晶结构的红荧烯薄膜,并对其形貌进行了分析。结果表明非晶结构的红荧烯薄膜首先在硅衬底上生长,非晶红荧烯薄膜生长至一定厚度后,多晶结构的红荧烯从其中形成。     

Surface effects on the wrinkles in a stiff thin film bonded to a compliant substrate

Surface effects are important to predict the mechanical behavior of nanostructures. In this paper, the wrinkling of a stiff thin film bonded to a compliant substrate is studied using an energy method accounting for surface elasticity and residual surface tension. The wavelength, critical buckling strain and amplitude are obtained analytically. These results provide valuable guide to the precise design and control of the wrinkling profile in many applications ranging from stretchable electronics to micro/nano scale surface patterning and precision metrology.