The use of GaN based electronic and photonic devices for bio-applications

Gateless AlGaN/GaN high electron mobility transistor(HEMT) structures exhibit large changes in source-drain current upon exposing the gate region to various block copolymer solutions. The polar nature of some of these polymer chains lead to a change of surface charges in gate region on the HEMT, producing a change in surface potential at the semiconductor/liquid interface. The nitride sensors appear to be promising for a wide range of chemical gas, combustion gas, liquid and strain sensing. We have also studied the effect of 370 nm UV light on fibroblast cell growth. At this wavelength, the UV light produced a strong inhibition of the cell growth. By employing a thin TiO ₂ film on the glass template for cell growth, most of UV light was reflected from the substrate and allowed the cells to grow. The TiO ₂ thin film can be patterned with standard photolithography followed by etching. Employing this technique, a 4 μn resolution of patterned cell growth was achieved. Based on the simulation results of using TiU2/SiO2 mirror stacks, 99.5% of UV light can be reflected from the TiO ₂/SiO ₂ coated area and even higher resolution and a lower intensity of UV light for selective area cell growth can be achieved.