Researchers at semiconductor manufacturer Infineon Technologies AG have succeeded, for the first time, in using carbon nanotubes to manufacture power semiconductors. Infineon scientists from Munich, Germany, have now demonstrated the first nanotube switch that can control light emitting diodes (LEDs) or electric motors. This is considered a breakthrough for nanotechnology, since scientists previously assumed that these miniature atomic-sized components were not suitable for the high voltages and currents used in power applications. Power semiconductors made of carbon nanotubes may one day make it possible to produce power switches that are much smaller and less expensive to manufacture than has been possible until now.
Nanotubes are microscopic “pipes” that are made out of carbon atoms and have a diameter of one millionth of a millimeter. A human hair is approximately 100,000 times thicker. These miniature tubes have already been used in research laboratories to make transistors for computer chips in order to store and process information, but only low voltages and currents are used for such tasks. On the other hand, the voltages and currents used in power transistors – such as the ones employed in electric motors, lamps or power supply units – are more than 1,000 times higher. These transistors serve as power switches with the primary objective of minimizing energy losses or eliminating the need for mechanical components. Currently, power semiconductors are made primarily of silicon, but their production process is relatively complex and expensive.
With their first prototype, Infineon researchers have demonstrated that carbon nanotubes can also function as power transistors. The prerequisite: Groups of hundreds or thousands have to be packed together in parallel. Infineon’s prototype can switch LEDs and small electric motors at a voltage of 2.5 volts. It consists of approximately 300 nanotubes arranged in parallel. The main advantages offered by the new type of power transistor can be seen in the significantly simpler manufacturing process, higher switching speeds, reduced heat development and in the high current densities that the tightly packed carbon tubes are able to withstand. Power transistors made of carbon nanotubes are still in the basic research stage. It is not yet clear how long it will be before they can be produced commercially in large numbers.