Electron beam induced deposition of iron

: exploring the surface processes governing EBID

  • M. Beljaars

Scriptie/masterproef: Master

Uittreksel

In this thesis the properties of iron depositions, created with Electron Beam Induced Deposition (EBID) are investigated. In EBID a precursor gas is introduced in a vacuum system, which adsorbs on a sample substrate. Subsequently the adsorbed molecules are decomposed in volatile and non volatile fractions by local irradiation with electrons. By precipitation of the non volatile parts a deposition is formed. The deposition of iron by means of EBID is relatively unexplored. The combination of the local, direct structuring capabilities of EBID and the ferromagnetic properties of iron are a promising combination for the field of Spintronics. Two different iron precursors, Fe3(CO)12 (TIDC) and Fe2(CO)9 (DINC), are investigated. Both these precursors are characterized by deposition yield, composition of the resulting depositions and, on a preliminary level, magnetic properties. Due to the limited flux of both precursors, the yield depends on the used beam current. Characteristic values for the yield of TIDC and DINC are 10?3 and 10?4 ?m3 nC?1 respectively at a electron beam current of 1 nA. The composition of the DINC depositions is found to depend on the beam current used to create the depositions. At low currents the found Fe content is 25 atomic %, which converges at high currents to 60 atomic %. The TIDC depositions are found to have a typical Fe content of 51 atomic %, independent of beam current. The preliminary magnetic characterization of the TIDC depositions show a paramagnetic, and possibly ferromagnetic behavior. The structures in the DINC depositions, visualized with MFM, strongly indicate a ferromagnetic ordering.The greater part of this thesis deals with the enhanced deposition at the edges, that can arise as a consequence of surface diffusion. In this part of the thesis the focus lies on the TIDC precursor. The TIDC precursor is shipped in methanol to protect it from air. This methanol is seen to be of great influence on the shape of the depositions. An experiment where isopropanol is introduced in the system confirms the significant effect of volatile contamination on the depositions. A analytical model and accompanying computer simulation is developed to study these shapes. Experimentally, diffusion is studied by the creation of depositions at different temperatures and different waiting times between consecutive deposition passes. It is observed that the depositions change shape with temperature and waiting time, in accordance with the model.
Datum Prijs31 aug 2008
TaalEngels
BegeleiderReinoud Lavrijsen (Afstudeerdocent 1), Henk J.M. Swagten (Afstudeerdocent 2), Bert Koopmans (Afstudeerdocent 2) & J.J.L. Mulders (Externe coach)

Citeer dit

Electron beam induced deposition of iron: exploring the surface processes governing EBID
Beljaars, M. (Auteur). 31 aug 2008

Scriptie/masterproef: Master