Fabrication of nanometer-scale pillar structures by using nanosphere lithography

In this work, we have successfully fabricated a periodic array of nanostructures on the GaN, sapphire and silicon substrates by using a nanosphere lithography. First, a polystyrene nanosphere monolayer with a diameter of 500 nm was spin-coated on the substrates; then, an oxygen plasma was applied to the monolayer using a reactive ion etching system to make spacings among the nanospheres so that one could control the on/off ratio of the pitch and the shape of the nanoscale pillar structures. Next, evenly-spaced polystyrene nanospheres were used as a mask for inductively coupled plasma reactive ion etching to make nanoscale pillar structures of different shapes and depths on the substrates. These experimental results are expected to offer a milestone for the application of nanostructures to various semiconductor devices.