Design and Fabrication of Nanostructure for Mid-IR Antireflection Surface Texturing Applications

Reduction of unwanted light reflection from a surface of a substance is very essential for the improvement of the performance of optical and photonic devices. Anti-reflection (AR) surface textures can be created on the surface of lenses and other optical elements to reduce the intensity of surface reflections. AR textures are indispensable in numerous applications, both low and high power, and are increasingly demanded on highly curved optical components. Nanofabrication involves the fabrication of devices at the nanometer scale. In this work, we used nanofabrication to design and fabricate nanostructures of squares and hexagons of different spatial pitch and gap width in Gallium Arsenide (GaAs). These structures have a gap of 300nm, 400nm, and pitch of 900nm, 1000nm and 1100nm. The fabrication process involves solvent cleaning, deposition of silicon oxide, soft and hard bake, photolithography and development. Both wet and dry etching were used to fabricate the expected structures. Results from scanning electron microscopy (SEM) to examine the shapes of the fabricated arrays are presented in this study. By combining dry and wet etches, we obtained the desired shapes and depth of hexagons and squares with rounded edges. We report detailed fabrication processes and their corresponding results at each step.