Oral Presentation 24th Australian Conference on Microscopy and Microanalysis 2016

In-situ fabrication of metal nanoparticles arrays for imaging (#128)

Yeonuk Kim 1 , Changxi Zheng 2 3 , Jing Fu 1
  1. Department of Mechanical and Aerospace Engineering, Monash University, CLAYTON, VIC, Australia
  2. Department of Civil Engineering, Monash University, CLAYTON, VIC, Australia
  3. Monash Centre for Atomically Thin Materials, Monash University, CLAYTON, VIC, Australia

The amplification of surface plasmonic response can be achieved by deposition of nanoscale metal features such as gold nanoparticles (AuNPs) 1, and by controlling their size and shape, optical, magnetic and electronic properties can be tuned for various applications 2 3. In this research, we fabricate controlled arrays of uniformly distributed AuNPs in situ with two different engineering approaches, followed by discussion of the characterization results and future applications. 

First, E-beam evaporation of Au is performed through a nanoscale stencil mask etched in a silicon nitride membrane with Focused Ion Beam (FIB) milling 4 5. This approach will enable fabrication of controlled size and array of sub-100 nm cylindrical features 4 6. In the experiment, low current ion beam with 30 kV of accelerating used to produce an array of 50 nm diameter nanoholes. This mask is then mounted on silicon wafer using a specially manufactured device, and a 50 nm of gold layer is deposited through the mask. The second approach is based on gold coating and direct FIB milling to produce ordered NP arrays, with milling patterns inversely calculated from the designed NPs.

Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were employed to characterize the NP arrays fabricated. While both approaches were capable of producing controlled size and arrays of AuNPs, nanostencil mask produced more accurate structures. However, total fabrication time was significantly reduced with the FIB direct milling method. Also, fabrication of AuNPs at arbitrary locations has been achieved with FIB direct milling, while alignment could be challenging using nanostencil towards a specific site. Both approaches are highly reproducible, although some gradual clogging occurred with the nanostencil approach. Considering the associated surface enhancement effect 3, the produced ordered arrays of AuNPs are expected to be a unique contribution to various integrated bio and optical devices.

  1. Moirangthem, R.S., Y.-C. Chang, and P.-K. Wei, Ellipsometry study on gold-nanoparticle-coated gold thin film for biosensing application. Biomedical Optics Express, 2011. 2(9): p. 2569-2576.
  2. Chithrani, B.D., A.A. Ghazani, and W.C.W. Chan, Determining the Size and Shape Dependence of Gold Nanoparticle Uptake into Mammalian Cells. Nano Letters, 2006. 6(4): p. 662-668.
  3. Masahiko, Y., O. Hiroki, and Y. Akinori, Rapid fabrication of an ordered nano-dot array by the combination of nano-plastic forming and annealing methods. Journal of Micromechanics and Microengineering, 2011. 21(12): p. 125017.
  4. Zhou, Y.X., et al., Simple Fabrication of Molecular Circuits by Shadow Mask Evaporation. Nano Letters, 2003. 3(10): p. 1371-1374.
  5. Kölbel, M., et al., Shadow-Mask Evaporation through Monolayer-Modified Nanostencils. Nano Letters, 2002. 2(12): p. 1339-1343.
  6. Tong, H.D., et al., Silicon Nitride Nanosieve Membrane. Nano Letters, 2004. 4(2): p. 283-287.