In-situ Investigation of the Mechanical and Electrical Properties of Nanosized Silicon Powders
- PDF / 1,295,003 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 76 Downloads / 164 Views
1083-R05-06
In-situ Investigation of the Mechanical and Electrical Properties of Nanosized Silicon Powders Ingo Pluemel, and Hartmut Wiggers Institute for Combustion and Gasdynamics and CeNIDE, University Duisburg-Essen, Lotharstr. 1, Duisburg, 47057, Germany ABSTRACT The electrical and mechanical properties of nanosized silicon powders were characterized in-situ under a uniaxial force. The resistance, impedance, and density were measured for different sample masses and mean particle sizes ranging from 3 to 50nm. The results reveal that powders of nanosized particles exhibit a completely different mechanical behavior during compaction compared to microsized particles. They show long-term creeping and large plastic deformation of the particle ensemble. This behavior is supposed to originate from comparably strong particle-particle forces which show a distinctive size-dependency. INTRODUCTION The use of nanosized silicon powders in nanoelectronics and photovoltaics enables new technologies and promises to reduce the production costs of devices like solar cells and printable electronics significantly. However, to understand the electrical behavior and mechanical properties of mesoscopic particle ensembles, such systems must be examined carefully. In porous systems like powders, the macroscopic electrical properties result from transport mechanisms such as hopping and tunneling between particles as well as from structural properties such as the number of particle contacts as well as the size and shape of these contacts. Theoretical approaches like the strongest stresses network [1] for the description of the mechanical properties, and the brick layer model [2] for the description of the electrical properties are useful tools to describe this complex relation in a simplified way. But for real applications they need to be accompanied by suitable experiments EXPERIMENT As sample material, nanosized pure and n-doped silicon powders synthesized in a microwave supported plasma reactor are used. Details of the production process were reported in [3]. The powders are characterized by determining in-situ the conductance, impedance, and density while a uniaxial mechanical force ranging from 10 to 100kN is applied in a stepwise manner. The force is applied to the cylindrical sample cell (diameter 13mm) shown in figure 1 along the cylinder axis using a hydraulic press. The force range corresponds to a pressure between 75 and 754MPa for the given experimental setup. The load plates of the sample cell are used as electrodes for the electrical measurements and by measuring the I/V-characteristic it is verified that they can be used as ohmic contacts. The density change of the powder during compaction was determined with high resolution by means of a laser interferometer.
Figure 1. Sample cell for powder characterization under a uniaxial force using a hydraulic press. The two electrodes are used for DC- and impedance measurements. The laser interferometer determines the change in density. RESULTS AND DISCUSSION Under a uniaxial forc
Data Loading...
