Advancement in Nanopatterning of Gallium Nitride Research using Sequential Infiltration Synthesis*

Group III nitride materials such as Gallium Nitride (GaN) are one of the greatly utilized semiconductor materials in optoelectronic and microelectronic applications because of their wide bandgap leading to broad emission and robustness of withstanding high temperature and pressure. However, the growth process is challenging because of the high-temperature requirements and lattice mismatch with conventional substrates. Among the emerging fabrication processes, sequential infiltration synthesis (SIS) derived from atomic layer deposition (ALD) has the potential to do controlled and precise fabrication of patterned nanostructures. It involves the alternate deposition of distinct precursor chemicals with distinct chemical interactions with a patterned polymer enabling selective infiltration for well-ordered and large-scale deposition of materials in the nanoscale. In this work, we are utilizing self-assembled polystyrene-block-poly(caprolactone) (PS-b-PCL) and polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymers as a template for SIS. The resultant nanostructures of GaN complex/compound were obtained by etching out the polymers after SIS. We observed 20-30 nm dimensions of nanoscopic patterns from scanning electron microscope (SEM) images and identified Ga and N elements from Energy-Dispersive X-ray Spectroscopy (EDS). The probable complex/compound formation was also characterized by analyzing Fourier Transform Infrared Spectroscopy (FTIR) spectra.