An ordinary integrated circuit is made of layers of material. Typically a layer is made from some material (like silicon dioxide, polysilicon, copper, or aluminum). Sometimes a process will modify parts of a layer (for example, using ion implantation to dope regions of silicon). Other times, some part of the layer will be cut away using a photolithography process.
Researchers at MIT have a new technique that allows super thin layers (1-3 atoms thick) and–even more importantly–enables you to use two materials in the same layer. They report that they have built all the basic components required to create a computer using the technique.
The prototype chips use two materials: molybdenum disulfide and graphene. The method apparently works with materials that combine elements from group six of the periodic table, such as chromium, molybdenum, and tungsten, and elements from group 16, such as sulfur, selenium, and tellurium.
To assemble their integrated circuits, the researchers first place a layer of graphene on silicon. Then they etch the regions where they wish to deposit the molybdenum disulfide. Next, at one end of the substrate, they place a solid bar of a material known as PTAS. They heat the PTAS and flow a gas across it. The gas carries PTAS molecules with it, and the molecules stick to the exposed silicon but not to the graphene. Wherever the PTAS molecules stick, they catalyze a reaction with another gas that causes a layer of molybdenum disulfide to form.