Selective adsorption of metallocenes on clean and chemically modified Si(111) surfaces

Abstract

Metallocene adsorption on clean Si͑111͒ and CaF 2 /CaF 1 /Si͑111͒ substrates has been investigated with scanning tunneling microscopy. The surface chemical composition is found to strongly change the adsorption site selectivity, leading to an enhanced edge selectivity on modified substrates. Templates with well-defined local chemical reactivity have been created via self-assembly. The selective adsorption of metallocenes on such tailored substrates facilitates patterning ordered arrays of magnetic nanowires and stripes on the single digit nanometer scale.

Structural transitions and relaxation processes during the epitaxial growth of ultrathinCaF2films on Si(111)

“…23 In addition, CaF 2 / Si͑111͒ has been used to for the self-organization of atomic wires via selective adsorption of metal organic molecules at atomic steps of vicinal substrates. [24][25][26] The key properties of CaF 2 films for all applications mentioned above are the large band gap and conduction-band offsets, respectively, as well as the high quality of ultrathin CaF 2 films deposited on Si͑111͒. The latter point strongly depends on the lattice matching between CaF 2 ͑111͒ and Si͑111͒.…”

Cobaltocene adsorption and dissociation on Cu(111)

“…The surface chemistry of many metallocenes, M(C 5 H 5 ) 2 (M = Cr, Mn, Fe, Co, Ni) has been motivated by the possibilities of "direct writing" small magnetic features [1][2][3][4][5][6][7][8][9][10][11][12]. "Clean" magnetic features require the removal of the ligand species during decomposition, which may require the addition of hydrogen to the background, but the metallocene interaction with the substrate is also key.…”

Self-assembled Fe nanowires using organometallic chemical vapor deposition and CaF2 masks on stepped Si(111)

“…We expose the patterned nanowires to ultraviolet photons from a nitrogen laser to dissociate the organic ligands from the ferrocene molecules. 6 This photolytic process has been proven to incorporate less carbon and oxygen into the growing Fe structures than using other methods, such as pyrolysis. 7 After the first Fe monolayer is deposited, the selective adsorption and photolysis processes continue.…”

“…6 As the substrate is covered by ferrocene, it becomes passive unless it is exposed to ultraviolet photons. We use a commercial a͒ Author to whom correspondence should be addressed; electronic mail: fhimpsel@facstaff.wisc.edu APPLIED PHYSICS LETTERS VOLUME 78, NUMBER 6 5 FEBRUARY 2001 nitrogen laser with an average power of 120 mW at a repetition rate of 15 Hz.…”

“…5, 6 The stripes do not touch each other due to their topological incompatibility. The incoming ferrocene prefers to anchor at the narrow CaF 1 trenches and at the edges of the CaF 2 stripes.…”