Single-layer semiconductors successfully grown in large thin films

Nature : Growing single-layer molecular semiconductors such as molybdenum disulfide has been possible for a while, but only on very small scales. Now, Jiwoong Park of Cornell University and his colleagues have adapted a technique that lets them grow single-layer semiconductors on 10-cm-diameter silicon wafers. Park’s team used a technique to grow the semiconductor atom by atom from gas at a high temperature. Previous attempts with that technique had produced inconsistent results. The semiconductors are three-atom-thick sandwiches of a transition metal , such as molybdenum, placed between two layers of chalcogens , such as sulfur. Like graphene, those transition-metal dichalcogenides are thin and flexible and can be peeled off layer by layer from a larger block of material. Park’s team was able to place multiple layers of the semiconductor on a single graphene wafer, which will allow not just the removal of layers, but also the construction of three-dimensional semiconductors.