Formation of nanoscale platinum and iron oxide structures using electron beam induced deposition techniques

Electron beam induced deposition (EBID) is a promising technique for fabricating nanometre-sized structures in a position-controlled manner. In this technique, organometallic precursors are decomposed by focused electron beams. Then, the non-volatile part of the decomposed precursor deposits on the substrate. As electron beams can be focused to a sub-nanometre scale in modern electron microscopes, the resolution of EBID is now reaching down to subnanometres. However, the deposits generally contain a large amount of amorphous carbon. This carbon contamination may be the most serious drawback and is preventing practical uses of EBID in nanodevice technology. In this study, nanostructures, such as nanowires, were fabricated by EBID using methyl cyclopenta dienyl platinum trimethyl (MeCpPtMe₃) and iron pentacarbonyl (Fe(CO)₅) precursors in a scanning electron microscope with a custom-made gas introduction system. After the deposition, nanostructures were heated at 400°C in air for 30 min. to remove contaminated carbon. Then, the nanostructures were observed using a transmission electron microscope (TEM). TEM observation revealed that a post-deposition heat-treatment in air resulted in the removal of carbon. The nanostructures made from MeCpPtMe ₃ and Fe(CO)₅ became pure Pt and a mixture of hematite and maghemite iron oxides, respectively.