Cornell University researchers have demonstrated a new technique for creating a semiconductor that is just a few atoms thick. They used a common semiconductor growing method to create molybdenum disulfide, a 2-D material that, like graphene, has been touted for retaining excellent electrical properties even when it is just a few atoms thick. This new material has previously been grown in disjointed single crystal formations, but in order for it to be a practical replacement for silicon in electronics, it will need to be in smooth, flat ultrathin sheets.
The Cornell team used metal organic chemical vapor deposition (MOCVD), a technique that starts with a powdery precursor, forms a gas, and sprinkles single atoms onto a substrate, one layer at a time. The researchers tweaked the method to create the thin semiconductor wafer. Throughout the experiment, they used advanced optical imaging techniques and advanced transmission electron microscopy for quality control. Additionally, they proved that the film they created can be made into thin electronic devices, by stacking alternating layers of molybdenum disulfide with silicon dioxide.
The Cornell team’s work went beyond molybdenum disulfide; they also used the same technique to make films out tungsten disulfide, which resulted in different electrical properties. The researchers plan to use the same process to make atomically thin films of many different materials to be used in ultrathin and flexible electronics, photovoltaics and display technology in the future. In the paper in Nature that describes their project, they wrote, “our work is a step towards the realization of atomically thin integrated circuitry.”