NC State researchers have developed a new way to transfer thin semiconductor films, which are only one atom thick, onto arbitrary substrates, paving the way for flexible computing or photonic devices. The technique is much faster than existing methods and can perfectly transfer the atomic scale thin films from one substrate to others, without causing any cracks.
The thin film is made of molybdenum sulfide (MoS2), which is hydrophobic --11/13/2014 it repels water. But the sapphire substrate the thin film is grown on is hydrophilic - it attracts water. Cao's new transfer technique works by applying a drop of water to the thin film and then poking the edge of the film with tweezers or a scalpel so that the water can begin to penetrate between the MoS2 and the sapphire. Once it has begun to penetrate, the water pushes into the gap, floating the thin film on top. The researchers use a tissue to soak up the water and then lift the thin film with tweezers and place it on a flexible substrate. The whole process takes a couple of minutes.