Variety of nanopatterns on different substrates using PS-b-PMMA and their applications

High density arrays of nanostructures over a large area can be formed on a range of substrates, such as glass, GaN, SiO2 deposited silicon wafer, etc. by the self-assembly of PS-b-PMMA block copolymers. The morphology of the polymer surface is strongly dependent on the thickness of the polymer layer. It is necessary to control the size and shape in order to get the desired properties. The deposition of a gold thin film on polymer-patterned glass followed by the removal of the remaining part of the polymer results in patterned gold on glass, which can be used as a transparent conducting electrode, where the conductivity and transparency depends on the thickness of gold and as well as on the connectivity of the gold pattern. Similarly, the polymer pattern can be transferred to an underlying GaN layer in an as grown LED, which increases the photoluminescence intensity making it useful as a photonic crystal.