Swiss researchers build silicon chip alternative

Swiss researchers have created the first computer chip made out of molybdenite (MoS2), a naturally occurring mineral that has been touted as a low-energy alternative to silicon.

The integrated circuit was made in the Laboratory of Nanoscale Electronics and Structures (LANES) at the École Polytechnique Fédérale de Lausanne (EPFL). The researchers said their experiments prove that molybdenite chips can be made smaller than silicon chips, use less electricity and be more flexible.

So far, it has not been possible to make layers of silicon less than two nanometers thick, because of the risk of initiating a chemical reaction that would oxidise the surface and compromise its electronic properties. Molybdenite, on the other hand, can be worked in layers only three atoms thick, making it possible to build chips that are at least three times smaller.

Even at this minute scale, the material remains stable and conduction is easy to control, according to LANES director Andras Kis.

Molybdenite can also rival silicon in its ability to amplify electronic signals, with an output signal that is four times stronger than the incoming signal. This means that MoS2 transistors are very energy-efficient, and Kis claims there is “considerable potential for creating more complex chips”.

Finally, the flexibility of molybdenite could make it suitable for use in flexible electronics, such as in the design of flexible sheets of chips. These could one day be used to manufacture computers that roll up or devices that could be affixed to the skin, the researchers said.

Molybdenite is being compared to graphene, another flexible semiconductor that many regard as the natural successor to silicon. Graphene is also extremely thin, consisting of a single layer of carbon atoms arranged in a honeycomb structure.

Earlier this year, IBM researchers build the first graphene-based integrated circuit, able to operate at frequencies of up to 10GHz, or 10 billion cycles per second. Today's silicon-based circuits can only scale to about 4GHz.

Experiments with graphene have revealed a multitude of other potential uses, including accelerating future high-speed Internet, manufacturing fast-charging batteries and improving the speed and density of printable electronics.

However, Kis's team identifies one key advantage that molybdenite has over graphene – it can amplify electronic signals at room temperature, while graphene must be cooled to 70 Kelvin (cold enough for nitrogen to turn into liquid).

Despite molybdenite's potential, the researchers say it will be at least 10 to 20 years before it enters commercial use. In the meantime the group intends to explore whether the material can be made more conductive.