Scanning Electron Microscopy of Semiconducting Nanowires at Low Voltages

Abstract

Light emitting para-hexaphenylene (p6P) nanofibers with typical widths of a few hundred nanometers and heights of a few ten nanometers are analyzed with the help of a field emission scanning electron microscope (FESEM). Charging effects are minimized by transferring the nanofibers onto silicon substrates and by applying very low acceleration voltages in the FESEM, down to 100 V. The resulting measured planar dimensions of the nanofibers (length and width) agree qualitatively with those measured by atomic force microscopy. At very low voltages the FESEM images also reveal significantly more detailed information from the surface of the nanofibers as compared to measurements performed at more conventional, high voltages of kilovolts. However, with increasing electron dosage charging and radiation-induced modification of the nanofibers is observed, leading to an apparent increase of width and length. We interpret this increase as being due to electron-induced polymerization at the interface between nanofibers and substrate