Potentially Thinnest-Possible Semiconductor Created
More and more it looks assured that we will see silicon be replaced in electronics with flexible and transparent materials. Researchers at the University of Washington have recently created a heterojunction between a pair of two-dimensional semiconductors that could find use in future technologies.
Heterojunctions are where two different materials meet and combine, and because of the combination, the junction itself possesses different properties than the two materials. In this case the two materials were molybdenum diselenide and tungsten diselenide, which are both monolayer materials and have similar structures. The similar structures greatly helped in forming the junctions without any distortions or discontinuities. To create the composite material, the researchers put a powder mixture of both materials in a chamber heated to 900 ºC and passed hydrogen gas through it. This caused some of the evaporated atoms to move over to a cooler part of the chamber, where they could form single-layer crystals. Thanks to the different properties of the materials, they evaporate at different times, so they go to the cooler region at different times as well. After the first material cooled and former triangular crystals, the second came over and attached to the edges, forming the heterojunction.
While this experiment only used molybdenum diselenide and tungsten diselenide, the process could be used to combine other two-dimensional materials to achieve a variety of properties for use as LEDs, photovoltaics, in-line quantum wells, and more. No matter the use though, the process should be fairly easy to scale up for mass production, by using a large furnace.
Source: University of Washington