| AVS 58th Annual International Symposium and Exhibition | |
| Energy Frontiers Focus Topic | Thursday Sessions |
| Session EN+NS-ThA |
| Session: | Nanostructures for Energy Storage and Fuel Cells II |
| Presenter: | Keith Gregorczyk, University of Maryland, College Park |
| Authors: | K.E. Gregorczyk, University of Maryland, College Park P. Banerjee, University of Maryland, College Park G.W. Rubloff, University of Maryland, College Park |
| Correspondent: | Click to Email |
Next generation nanostructured devices require ultrathin layers of different materials (e.g. current collectors found in solar cells, batteries, and charge storage and memory devices, etc.). However, in the ultrathin regime, expectations from bulk resistivity can be misleading in designing such nanostructures. Here, we show the example of ultrathin (5-24nm) Ru films produced by atomic layer deposition (ALD), where resistivity is dramatically increased: at 5nm resistivity is ~7X higher (~135 μΩ cm) than at 24nm (~20 μΩ cm) and ~18X higher than bulk Ru (7.4 μΩ cm). The drastic differences seen here are explained through Mayadas-Shatzkes (MS) theory, which defines the increase in resistivity through geometrical constraints (e.g. film thickness and grain boundaries). Using MS theory the grain boundary reflection coefficients were calculated as ~0.32 for an 18nm thick film and ~0.66 for a 5nm film. Furthermore, the electrical transport properties of these films were studied as a function of both temperature (80-340K) and film thickness (5-24 nm). Finally, we show that the ALD Ru films are p-type, in agreement with the theory of compensated metals, and report both the temperature coefficient of resistivity and charge carrier mobility as a function of film thickness.