| AVS 58th Annual International Symposium and Exhibition | |
| Nanometer-scale Science and Technology Division | Tuesday Sessions |
| Session NS-TuM |
| Session: | Nanowires and Nanoparticles II: Characterization and Synthesis |
| Presenter: | John Hammond, Physical Electronics |
| Authors: | J.S. Hammond, Physical Electronics D.F. Paul, Physical Electronics U. Given, Northwestern University |
| Correspondent: | Click to Email |
The incorporation of electrically active dopants into nanowires (NW) is essential to the development of semiconductor NWs based electronic devices. The ability to engineer the electrical properties of nanowires grown by the vapor liquid solid (VLS) process is currently limited by our incomplete understanding of the doping mechanism. Recently, several studies have shown evidence of inhomogeneous radial dopant distributions in Si NWs and the resulting effects on their electrical properties [1-2]. However, the longitudinal dopant profile has not been addressed to the same extent. Studies employing both indirect and direct measurement techniques (such as scanning photocurrent microscopy, Kelvin probe force microscopy and atom probe tomography) have addressed variations in longitudinal dopant profiles in Si NWs and related them to radial dopant variations induced by the growth process [3-4]. There have not yet been direct measurements of dopant concentrations along VLS grown nanowires. We have measured the longitudinal and radial doping profiles of phosphorus doped, untapered Si NWs using scanning Auger. We have found order of magnitude enhancements in the dopant concentration toward the NW's base as expected from previous indirect measurements. Importantly, the physical dopant profile is not identical to the active dopant profile, as shown by comparison with scanning photocurrent microscopy and Kelvin probe force microscopy measurements. The resolution and sensitivity of scanning Auger as an analytical tool for dopant concentration measurements will be compared to the other available techniques to indicate unique capabilities that can advance our understanding of nanowire doping.
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[2] P. Xie, Y. Hu, Y. Fang, J. Huang and C.M. Lieber, Proc. Natl. Acad. Sci. USA 2009, 106, 15254-15258; E. Koren, N. Berkovich, and Y. Rosenwaks, Nanoletters, 2010, 10, 1163-1167.
[3] J. E. Allen, D. E. Perea, E. R. Hemesath, and L. J. Lauhon. Adv. Mater. 2009, 21, 3067–3072.
[4] E. Koren, Y. Rosenwaks, J. E. Allen, E. R. Hemesath, and L. J. Lauhon. Appl. Phys. Lett. 2009, 95, 092105.