R. Rai, U. Dhakal, D.C. Binod, Y. Miyahara
Texas State University,
United States
Keywords: SEM, FEBID, AFM, EDS, nanowires, resistivity, platinum
Summary:
Focused Electron Beam Induced Deposition (FEBID) is an advanced direct-write nanofabrication technique used to create intricate, three-dimensional (3D) nanostructures [1]. FEBID does not require any masks and multi-step processes like resist coating and etching. The electron beam dissociates the precursor adsorbed on a substrate, leaving the desired material as a deposit, meanwhile volatile by-products are removed, enabling high-precision, localized deposition. This approach provides versatility in material choice and simplifies fabrication, making it ideal for rapid prototyping and highly customized nanoscale designs. Nanoelectrodes deposited via FEBID tend to bear high resistance because the deposition results in a mixture of platinum with undesired precursor elements, such as carbon, derived from the precursor Me3CpMePt (IV) (Me: Methyl, Cp: Cyclopentadienyl) [2,4]. We measure the electrical properties of Pt nanowires deposited by FEBID technique. FEBID deposition was carried out using a Scanning Electron Microscope (Helios Nano Lab 400). Post-deposition processing methods were explored to convert the deposited nanowires into conductive, pure platinum structures [3]. The as-deposited nanowires were annealed at 225°C in air for 30 minutes to 4 hours, which led to a five-order-of-magnitude improvement in electrical conductance. The lowest resistivity of 50 nm wires we measured is found to be 79.2 µΩ cm, which is 7 times higher than the bulk value for Pt [5]. The relative carbon and platinum ratio changes from 80 % to 20 % to 14 % to 86 % percent by weights. Annealing reduces the thickness of these nanowires roughly to 1/4th of the original size. Carbon content can be eliminated by 90 percent on 5 um × 50 nm nanowire. After annealing, these wires with thickness dimensions as low as 5 nm can maintain metallic conduction down to temperatures as low as 100 mK. [1] M. Huth, F. Porrati, and O. Dobrovolskiy, “Focused electron beam induced deposition meets materials science,” Microelectronic Engineering, vol. 185-186, pp. 9–28, Jan. 2018. [2] J.-Y. Fang, S.-Q. Qin, X.-A. Zhang, D.-Q. Liu, and S.-L. Chang, “Annealing effect of platinum-incorporated nanowires created by focused ion/electron-beam-induced deposition,” Chinese Physics B, vol. 23, p. 088111, Aug. 2014. [3] Lerma, J. A. H. Characterization of Deposited Platinum Contacts onto Discrete Graphene Flakes for Electrical Devices. [4] Z. A. K. Durrani, M. E. Jones, C. Wang, M. Scotuzzi, and C. W. Hagen, “Electron transport and room temperature single-electron charging in 10 nm scale Pt-C nanos-structures formed by electron beam induced deposition,” Nanotechnology, vol. 28, p. 474002, Nov. 2017. [5] "Resistivity of Various Materials," HyperPhysics, Georgia State University,[Online].Available:http://hyperphysics.phy-str.gsu.edu/hbase/Tables/rstiv.html. [Accessed: Dec. 16, 2024].