Faculty Sponsor's Department:
Reflection and transmission of light at interfaces can be controlled by structuring a surface with sub-wavelength spatial features. The moth eye is an example of this where tapered protuberances on the surface provide a continuous gradient in refractive index from air to the tissue, resulting in broadband anti-reflectivity. This approach can be extended to inorganic materials for ultra-broadband anti-reflective surface coatings in the infrared. Experimentally, this structure is realized on Si using a combination of colloidal lithography and reactive ion etching (RIE). However, traditional RIE with a capacitive antenna can cause sputtering damage, scalloping and artifacts. To eliminate these issues, an inductively coupled plasma (ICP) reactor was designed and built to achieve highly anisotropic etching with minimum sputtering damage.