Helmholtz-Zentrum Dresden-Rossendorf (HZDR)

Noteworthy is the fact that the processes they use are already employed in the production of semiconductors. “Indium arsenide is characterised by extremely high electron mobility,” explains Prucnal, a postdoctoral researcher. The electrons shoot through the material 30 times quicker than through a silicon wafer, which means the material can be used to produce faster components. “Moreover, the process requires only a low operation voltage,” adds Skorupa, head of the Semiconducting Materials Division. “As a result, less electricity is required and heat loss is significantly reduced.” The indium arsenide quantum dots are produced on freestanding silicon columns and are shaped like miniscule pyramids. These pyramids are around 100 nanometres high and have edges measuring between 40 and 80 nanometres. When a voltage is applied to this configuration, it behaves like a diode. In order to manufacture the quantum dots from indium arsenide, the researchers use ion implantation and short-term annealing, both of which are employed in “doping” in the semiconductor industry. Using the HZDR’s ion accelerator, they implant arsenic and indium ions in the surface of the silicon. A novel aspect of this approach is the generation of quantum dots in the millisecond range by means of liquidphase processing. As a semiconducting material, indium arsenide also has potential applications for optoelectronics, in which electrical signals are converted into light. The researchers are therefore also testing other semiconducting compounds such as indium phosphide and gallium arsenide, which radiate light at shorter wavelengths and are therefore better suited to photonic applications.

HZDR/Red.