Advancing Nanopatterning of Gallium Nitride Research with Sequential Infiltration Synthesis

The field of nanopatterning of inorganic materials has attracted significant attention in research labs and industries, including optoelectronics and photonics, due to their unique properties at the nanoscale and the compact geometry that helps in developing new devices with higher efficiency and better performances. Gallium Nitride (GaN), a group III Nitride material is one of most widely researched and utilized material for optoelectronic and power electronic research because of their wide bandgaps leading to emission in the Ultraviolet (UV) and Visible wavelengths and robustness leading to withstand high temperature and pressure. The growth of nitride materials is in general challenging because of high-temperature requirements and lattice mismatch with conventional substrates like Silicon. In the applied nanomaterials chemistry lab at ISU, we are developing a nanopatterning method of GaN at comparatively lower temperatures (100-150^oC) with easy integration steps to existing technology using a method called Sequential Infiltration Synthesis (SIS). SIS involves the alternate deposition of distinct precursor chemicals onto a patterned polymeric substrate to form the compound material, where the patterned polymer serves as a guiding matrix, enabling selective infiltration for well-ordered and large-scale deposition of materials in the nanoscale. Using SIS can lead to new, cost-effective substrate-independent nitride-based optoelectronic device applications. For nanopatterning GaN, we use polystyrene-b-polymethylmethacrylate (PS-b-PMMA) self-assembled nanostructures as a guiding pattern and infiltration of the inorganic GaN based and nitrogen-containing precursors in sequence to form nanoscopic patterns of GaN. The polymers are etched out by a plasma etching at the end to form GaN only nanostructures. We investigate the growth mechanism of these nitride inorganic materials using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Electron Spectroscopy (EDS), and Fourier Transform Infrared Spectroscopy (FTIR).