Laser‐Induced Direct Lithography for Patterning of Carbon with sp³ and sp² Hybridization

Abstract

A new method of laser‐induced lithography for direct writing of carbon on a glass surface is described, in which deposition occurs from a transparent precursor solution. At the glass–solution interface where the laser spot is focused, a micro‐explosion process takes place, leading to the deposition of pure carbon on the glass surface. Transmission electron microscopy (TEM) analysis shows two distinct co‐existing phases. The dominant one shows a mottled morphology with diffraction typical of cubic (sp3) diamond. The other region shows an ordered array of graphene sheets with diffraction pattern typical of sp2‐bonded carbon. The sp3 crystallites range in size from 9 to 30 Å and are scattered randomly throughout the sample. A UV Raman spectrum shows a broad band at the location of the expected diamond peak, together with a peak corresponding to the graphite region. We conclude that the patterned carbon is composed of a mixture of nanocrystalline sp3 and sp2 carbon forms.

Laser‐Based Printing: From Liquids to Microstructures

“…When laser illumination provides heat above a certain threshold, thermally driven reactions that promote material deposition in 2D and 3D can occur. [ 156 ] These methods were referred to as laser‐induced hydrothermal growth, [ 166 ] laser‐assisted hydrothermal method, [ 167 ] laser‐induced direct selective growth, [ 42 ] photothermal chemical liquid growth, [ 168 ] optothermal‐effect‐based mechanism, [ 169 ] laser‐induced solvothermal voxels, [ 170,171 ] direct‐write lithography, [ 172 ] laser‐induced direct lithography, [ 173 ] and in situ laser patterning technique. [ 174 ]…”

“…[ 170 ] Other demonstrations utilizing a mixture of precursors include formation of the molecular compound MoS 2 , [ 172 ] as well as AgBr [ 172 ] and Ag‐PVP. [ 172 ] Thermally driven reactions were also shown to decompose organic materials, resulting in patterns that consist of carbon [ 173 ] and Cu@C. [ 174 ] While most of the studies above focused on the formation of micro‐patterns (Figure 8b), some showed that without moving the stage during laser illumination and maintaining low reaction rates, discrete nanowires of ZnO and TiO 2 [ 166,167,169,175 ] can be formed (Figure 8c). Crystalline seeds (such as ZnO) can be pre‐deposited in order to allow faster initiation of the deposition of nanowires.…”

“…The minimum diameters of the microstructures (where circular deposition was obtained) and linewidths of the patterned structures were ≈ 0.7-500 µm. [166][167][168][169][170][171][172][173][174][175] A useful application that was demonstrated utilizing this method is enhancement of SERS signals. [169] In addition, fabrication of simple 3D structures was shown by thermal growth of iron oxide (Figure 8c) [168] as well as fabrication of multiple layers of various materials, sometimes considered as 2.5D printing (Figure 8d).…”

“…Wavelength [nm] 405, [169] 532, [166][167][168]175] 750, [171] 760, [170] 808, [174] 830, [172,173] 980 [173] Laser power [mW] 0.45-165 [166][167][168][169][170][171][172][173]175] Objective lens 5 ×, [166,168,175] 10 ×, [174] 20 ×, [166,168] 40 ×, [173] 60 ×, [170] 100 × [171,172] NA: 0.45, [169] 1.3, [170,171] 1.4 [170] Printing velocity Pattern formation: ≈1 µm s −1 -10 mm s −1 [170][171][172][173][174] Growth of nanowires: 0.3-3.5 µm min −1 [166][167][168][169]175]…”

“…Glass, [170][171][172][173][174] quartz, [173] polyimide, [173] mica, [172] metal coated substrate, [165,[167][168][169]171,174] glass modified with tetraethylorthosilicate (TEOS), [171] PMMA [172] Continuous phase Water, [166][167][168][169][170][171][172]175] ethanol, [166,173] isopropyl alcohol, [173] NMP, [173] toluene [173] www.afm-journal.de www.advancedsciencenews.com…”