Minimizing Reflectivity by Etching Microstructures in Mercury Cadmium Telluride (HgCdTe)

Mercury cadmium telluride HgCdTe is a semiconductor alloy used as an infrared detector material. In this study, the objective is to reduce reflectivity through the creation of sub-wavelength photonic microstructures. HgCdTe first undergoes a photolithography process using a photomask pattern to create positive and negative photoresist profiles. The patterned samples are then dry etched via inductively coupled plasma ICP, which uses argon Ar ions to physically liberate Hg, Cd, and Te from the surface. The reflectivity of the etched features is then measured. The resulting tapered pillar and hole structures in the HgCdTe produce a graded refractive index effect, which minimizes the reflection, hence improving photon absorption. Minimized reflectivity contributes to reduced detector noise and reduced signal loss advantages that cannot be acquired from untreated material.