Poster Presentation 26th ACMM “2020 Visions in Microscopy”

Towards functional nanostructures with focused ion beam (#236)

Vivek Garg 1 2 3 , Bhaveshkumar Kamaliya 1 2 4 , Shi Qiu 1 , Tsengming Chou 5 , Amelia Liu 6 , Alex de Marco 7 , Ajay Singh Panwar 8 , Rakesh G. Mote 3 , Jing Fu 1
  1. Mechanical and Aerospace Engineering, Monash University, Melbourne, VIC, Australia
  2. IITB Monash Research Academy, Mumbai, Maharashtra, India
  3. Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
  4. Department of Physics, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
  5. Laboratory of Multiscale Imaging, Stevens Institute of Technology, Hoboken, NJ, USA
  6. School of Physics and Astronomy, Monash University, Melbourne, VIC, Australia
  7. Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC, Australia
  8. Department of Metallurgical Engineering & Materials Science, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India

3D micro-nanostructures find a myriad of multidisciplinary applications in science and technology, such as optics, photovoltaics, micro-fluidics, bio-photonics, medical devices, anti-bacterial surfaces [1]–[3] etc. Conventional lithography techniques, used to fabricate micro-nanostructures commercially, pose tremendous challenges on mask preparation, and 3D structures are nearly impossible. Focused ion beam has evolved as a tool for rapid prototyping of microsystems owing to its one-step, mask-less fabrication capability, and high resolution [4].

This work aims at fabrication of nanoscale functional structures for diverse applications like anti-reflection, color filters, controlled manipulation etc. The nature of accelerated ions in FIB is directly used and subwavelength nanostructures are fabricated in a single-step on high index silicon (Si) [5]. The gaussian pillar shaped nanostructures, confirmed through calculations and experiments, enable broadband light tapping and antireflection properties. The fabricated tapered Si nanoholes also offer color filtering in reflection mode via selective absorption of narrow band of incident light wavelengths, facilitating multicolor generation [6]. The approach is demonstrated for high resolution color printing applications via fabrication of butterflies and letters on Si. Further, freestanding 3D Si nanostructures, combining FIB implantation with wet chemical etching are developed and employed for in-situ ion induced bidirectional bending for developing designed complex 3D nanostructures, such as ultra-long NWs, folded nanomesh, bacterial lobster trap [7] etc. Molecular dynamics (MD) simulations together with finite element analysis (FEA) help understanding the bending mechanism. In summary, the direct fabrication and strain-engineering with ion-beam pave the way towards a versatile platform for facile fabrication of 3D nanostructures with anticipated functionalities and future nanoscale devices, opening new avenues in the diverse field of ion beams and applications beyond material science.