The resistance of copper wires not only leads to speed limitations but also result in energy losses. The problem with light signals that computer chips consist of silicon, which is very inefficient in producing light. Direct semiconductors are much more suitable for producing light, but can only be integrated in a chip with an uneconomically high effort.
The research group led by Martyna Grydlik and Moritz Brehm of the Institute for Semiconductor and Solid State Physics at the University of Linz have succeeded in generating quantum dots i.e. objects with a size of just a few millionths of a millimeter on a silicon surface and then getting them to glow. “Our quantum dots consist of germanium, a material which can be applied to silicon in a relatively easy manner”, Brehm said. “It is not suitable as a source of light, just like silicon. However, the special structure of the quantum dots enables an efficient generation of photons“, he added.
The quantum dots serve as tiny cages for the charge carriers involved in producing the light. “By confining them, they become suitable for producing photons on the basis of quantum physical effects“, Brehm concluded.
The new method is still only a proof of concept trial. Stimulating the quantum dots does not take place by using electricity, as would necessary in using a chip, but by using an external light. According to the researchers, it should be possible to adapt the method. In this way, electrical signals could be converted into optical signals in the future, and thus be transmitted within the chip.