Transparent Conductive AlGaN/GaN Coatings for EMI/RFI Attenuation

In this SBIR program, Structured Materials Industries, Inc (SMI) and partners will develop an electrically conductive, optically transparent coating for attenuation of electromagnetic interference (EMI) and radio frequency interference (RFI). The proposed coating will be based on the wide bandgap semiconductor gallium nitride (GaN). GaN is transparent to radiation below its bandgap (Eg = 3.4 eV), and therefore an excellent candidate for optically transparent coatings in the 0.4µm to 5.0µm wavelength range. The electrical conductivity of GaN can be controlled over a wide range through modifications to the film composition or structure. GaN is also refractory and chemically stable, and should be resistant to salt spray, abrasion and solar radiation. The other key aspect of our technical approach is the use of metal organic chemical vapor deposition (MOCVD) to deposit the AlGaN/GaN based EMI/RFI attenuation coatings. MOCVD provides for excellent control of film composition and doping profiles, as well as easy scale-up to large area substrates, which can be either planar or 3-dimensional.