Researchers embed InAs crystals into Si nanowires
A group of researchers from Germany, Austria and Poland has taken a quantum leap in the development of an integrated chip that can accommodate very fast and multi-functional processing units with hybrid nanowires, produced by embedding nearly perfect semiconductor crystals into a silicon nanowire.
Nano-optoelectronics are considered the cornerstone of future chip technology, but the research faces major challenges. First, electronic components must be accommodated into smaller and smaller spaces. Second, what are known as compound semiconductors require that they be embedded into conventional materials. In contrast to silicon, many of such semiconductors with extremely high electron mobility could improve performance of the most modern silicon-based CMOS technology.
An illustration from energy-dispersive X-ray spectroscopy: InAs (green-cyan) is perfectly integrated into the silicon nanowire (blue). Source: Slawomir Prucnal, HZDR
Scientists from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Vienna University of Technology and Maria Curie-Sk?odowska University Lublin managed a near-perfect production and embedding of the indium arsenide (InAs) crystals into silicon nanowires for the first time.
This integration of crystals was the greatest obstacle for such "hetero-nanowires" until now. Beyond the nanometre range, crystal lattice mismatch always led to numerous defects.
In order to carry out this process, ion beam synthesis and heat treatment with xenon flash-lamps were used, provided by the Ion Beam Centre of the HZDR.
The scientists initially introduced a determined number of atoms precisely into the wires using ion implantation. They then carried out the flash-lamp annealing of the silicon wires in their liquid-phase within a matter of only 20ms.
"A silicon oxide shell, measuring merely fifteen-nanometers-thick, maintains the form of the liquid nanowire, while the implanted atoms form the indium-arsenide crystals," explained Dr. Slawomir Prucnal, HZDR scientist.
The rate at which the atoms diffuse in the liquid-silicon phase led to the formation of flawless mono-crystals with nearly perfect interfaces, according to Prucnal.
Taking the research to the next level, the scientists are looking at implementing different compound semiconductors into Silicon nanowires, as well as optimising the size and distribution of the crystals.
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