Atom-Thick Semiconductor Thin Films Grown
The current means of fabricating computer chips and other silicon technologies involves taking the semiconductor in bulk form and etching away unwanted portions. While this has served us well for decades, we are approaching this technique's limit, as well as the limit of silicon, so researchers have been looking to other production methods and other materials. Now researchers at North Carolina State University have found a way to grow thin films of the semiconductor molybdenum sulfide (MoS2) as thin as one atom thick.
Molybdenum sulfide is a somewhat special semiconductor as it is inexpensive and can be grown layer by layer using a vapor deposition technique. By placing sulfur and molybdenum chloride powders in a furnace, it is possible to vaporize the materials and make them react to form MoS2, which will fall on a substrate. This has been known for some time, but the researchers have refined the process by tuning two important pressures; the partial and vapor pressures. Partial pressure is the pressure of particles in the air to collect on a substrate, while vapor pressure is the pressure of particles on a substrate to jump back into the air. By carefully calibrating them, it is possible to limit the number of layers MoS2 that form.
Now that they have found a way to produce atom-thick sheets of a semiconductor, the researchers are investigating what they can do with it. The current focus is on creating field-effect transistors and LEDs, as well as modifying the technique so specific atomic layers can be made of other materials.
Source: North Carolina State University