| AVS 65th International Symposium & Exhibition | |
| In-situ Microscopy, Spectroscopy, and Microfluidics Focus Topic | Monday Sessions |
| Session MM+AS+NS+PC-MoM |
| Session: | Mechanical, Electrical, Thermal and Optical Systems for In situ TEM (9:00-10:100 am)/Beam Induced Effects and Processing in Liquid/Gas Cells for TEM/SEM (10:40-11:40 am) |
| Presenter: | Lunjie Zeng, Chalmers University of Technology, Gothenburg, Sweden |
| Authors: | L.J. Zeng, Chalmers University of Technology, Gothenburg, Sweden C. Gammer, Austrian Academy of Sciences, Austria B. Ozdol, Lawrence Berkeley National Laboratory T. Nordqvist, University of Copenhagen, Denmark P. Krogstrup, University of Copenhagen, Denmark A.M. Minor, Lawrence Berkeley National Laboratory W. Jäger, Chalmers University of Technology, Gothenburg, Sweden E. Olsson, Chalmers University of Technology, Gothenburg, Sweden |
| Correspondent: | Click to Email |
III-V semiconductor nanowires possess outstanding electronic and mechanical properties that can be utilized in future high-speed electronic devices, solar cells and sensors. To better understand these properties and their relations to the microscopic structure of the nanowires, it is critical to directly correlate the structure and properties of single nanowires. However, the direct characterization of the mechanical and electrical properties of single nanowires, in particular, the correlation between them is still a challenge. In this study, we directly investigate the intrinsic mechanical and electromechanical properties of individual InAs nanowires using in situ transmission electron microscopy (TEM).
Quantitative stress, strain and electrical transport measurements were carried out on single InAs nanowires simultaneously. A Hysitron PI95 nanoindentation TEM holder was used for the in situ TEM study. By using an electrical push-to-pull (EPTP) device in the in situ TEM holder, tensile stress was applied via the nanoindenter in the holder while the force applied on the nanowire was measured by a transducer in the holder. The EPTP device also enables current-voltage (I-V) measurements on single nanowires. Nanoscale lattice strain mapping within the nanowire was performed using scanning transmission electron microscopy (STEM) combined with nanobeam electron diffraction (NBED). NBED diffraction patterns were acquired using a Gatan K2 direct detection camera. Based on the detailed strain and stress measurements, Young’s modulus and Poisson’s ratio of single InAs nanwires were directly determined. The Young’s modulus of single InAs nanowire is smaller than that of the bulk, while the Poisson’s ratio of the InAs nanowire is similar as the bulk InAs. The electrical measurements showed that the resistivity of the InAs nanowires decreased continuously with increasing tensile stress. The piezoresistance coefficient of the nanowire was found to be significantly larger than that of bulk InAs. Moreover, significant inhomogeneous strain distribution within the nanowire under stress was unveiled by STEM-NBED strain mapping. The inhomogeneous strain distribution at nanometer scale can increase the resistivity of the nanowire by enhancing electron scattering. The findings demonstrate unique mechanical and electromechanical properties of the nanoscale InAs wires and provide new insights of the correlation between mechanical strain and electrical transport properties in free-standing nanostructures.
Financial support from Swedish Research Council and Nanoscience and Nanotechnology Area of Advance at Chalmers University of Technology are acknowledged.