Binary Mn–Si nanostructures prepared by focused electron beam induced deposition from the precursor SiH₃Mn(CO)₅

Abstract

Mixed-metal carbonyls are a family of compounds which can be used to fabricate bimetallic nanostructures by means of focused electron beam induced deposition. In the present work, we show that silicon-metal alloys can be prepared by using silyl-metal carbonyls. In particular, we employ the SiH 3 Mn(CO) 5 precursor to fabricate Mn-Si alloy nanowires, with composition of about 34 at% Mn, 17 at% Si, 31 at% C and 18 at% O, as revealed by energy dispersive x-ray analysis. Magnetotransport measurements are carried out on as-grown samples and on samples treated after-growth by low-energy electron irradiation. All the samples exhibit a quasimetallic temperature-dependent behavior. Hall-effect measurements indicate either electronlike transport, for as-grown samples, or hole-like transport, for post-growth treated samples, respectively. Correspondingly, the charge carrier density increases from n ≈ 10 20 cm −3 to n ≈ 10 22 cm −3 . We find a small negative transversal magnetoresistance, which depends on irradiation dose and temperature. Microstructural investigations carried out by transmission electron microscopy indicate that the samples are constituted by an amorphous Mn 2 Si phase embedded in a carbonaceous matrix. Additionally, in treated samples a novel Mn 2 SiO 4 spinel oxide phase is observed.

Direct Writing of Cobalt Silicide Nanostructures Using Single-Source Precursors

“…For the manganese derivative, the Mn:Si ratio has been found consistently to be close to 2, which indicates selective loss of silyl groups. 27 The observed retention of Si here could be associated to a stronger Co−Si bond in the precursor indicated by a blue shift in the infrared absorption band of the trans-located CO ligand in the Co derivative. 25,28 The most significant change in composition for CoSi is the drop in oxygen content from 21 at % for 0.098 nA to 15 at % at 6.3 nA beam current.…”

New precursors for direct writing of nanostructures using charged particle beams

“…This would also agree well with results reported for the thermal decomposition of H3SiMn(CO)5 at TS = 444 K inside an SEM. 197 Interestingly, selective loss of silicon containing fragments is observed, resulting in a Mn:Si ratio of about 1.5:1, also in good agreement with CVD experiments and FEBID deposition. 197 A potential reaction that could cause the Si loss is thermally activated dimerization of two H3SiMn(CO)5 molecules, forming H2Si(Mn(CO)5)2 and SiH4, indicated in thermal stability experiments.…”

“…195 Besides homometallic molecules, some heteronuclear compounds have been investigated as potential precursors for beam induced deposition, even though only very few have been actually used for FEBID and, to the best of my knowledge, none for FIBID, prior to this work. 40,49,52,115,[196][197][198] Not only can they be used for the deposition of alloys with defined stoichiometry they also allow for the investigation of differences in electron-induced decomposition depending on the central atoms of the precursor. Heteronuclear precursors will be discussed in detail in chapter 2.5.2 below.…”

“…H3SiMn(CO)5 was the first silyl substituted carbonyl precursor investigated for FEBID. 197 A high vapor pressure is observed due to its small molecular mass and weak intermolecular forces.…”

Writing 3D Nanomagnets Using Focused Electron Beams

“…It therefore comes as no surprise that several attempts have been made to fabricate alloy nanostructures by FEBID (see [ 57 ] for a more complete account). So far, three different approaches have been taken, namely (i) using two or three precursors in parallel [ 57 , 58 , 59 ], (ii) electron-beam or thermally induced intermixing of FEBID multilayer structures [ 60 , 61 ] and (iii) employing heteronuclear precursors [ 62 , 63 ].…”