High-aspect ratio micro- and nanostructures enabled by photo-electrochemical etching for sensing and energy harvesting applications

  • Badriyah Alhalaili
  • Daniel M. Dryden
  • Ruxandra Vidu
  • Soroush Ghandiparsi
  • Hilal Cansizoglu
  • Yang Gao
  • M. Saif Islam
Original Article
  • 2 Downloads

Abstract

Photo-electrochemical (PEC) etching can produce high-aspect ratio features, such as pillars and holes, with high anisotropy and selectivity, while avoiding the surface and sidewall damage caused by traditional deep reactive ion etching (DRIE) or inductively coupled plasma (ICP) RIE. Plasma-based techniques lead to the formation of dangling bonds, surface traps, carrier leakage paths, and recombination centers. In pursuit of effective PEC etching, we demonstrate an optical system using long wavelength (λ = 975 nm) infra-red (IR) illumination from a high-power laser (1–10 W) to control the PEC etching process in n-type silicon. The silicon wafer surface was patterned with notches through a lithography process and KOH etching. Then, PEC etching was introduced by illuminating the backside of the silicon wafer to enhance depth, resulting in high-aspect ratio structures. The effect of the PEC etching process was optimized by varying light intensities and electrolyte concentrations. This work was focused on determining and optimizing this PEC etching technique on silicon, with the goal of expanding the method to a variety of materials including GaN and SiC that are used in designing optoelectronic and electronic devices, sensors and energy harvesting devices.

Keywords

Silicon Photo-electrochemical etching Surface damage effects Optoelectronic devices 

Notes

Acknowledgements

The author gratefully acknowledged the financial support by Kuwait Institute for Scientific Research and the National Science Foundation (NSF CMMI-1445097).

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Electrical and Computer EngineeringUniversity of CaliforniaDavisUSA
  2. 2.Department of Materials Science and EngineeringUniversity of CaliforniaDavisUSA
  3. 3.Lawrence Livermore National LaboratoryLivermoreUSA

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