Scientists embed nearly perfect InAs crystals into nanowires
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the Vienna University of Technology and the Maria Curie-Skodowska University Lublin have for the first time successfully embedded nearly perfect indium arsenide semiconductor crystals into a silicon nanowire.
Silicon 'hetero-nanowires' integrated with III-V segments is considered a highly promising candidates for future high-speed and multifunctional nanoelectronic devices. However one of the major obstacles for in building such structures has been the numerous defects caused by crystal lattice mismatch at these dimensions.
In this case, the researchers used ion beam synthesis and heat treatment with xenon flash-lamps, two technologies in which the Ion Beam Center of the HZDR has held experience for many years. They initially needed to introduce 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 twenty milliseconds. "A silicon oxide shell, measuring merely fifteen-nanometers-thick, maintains the form of the liquid nanowire," explains HZDR scientist Slawomir Prucnal, "while the implanted atoms form the indium-arsenide crystals."
Wolfgang Skorupa, head of the research group adds: "The atoms diffuse in the liquid-silicon-phase so rapidly that within milliseconds they form flawless mono-crystals delineated from their surroundings with nearly perfect interfaces." In the next step, the scientists want to implement different compound semiconductors into silicon nanowires and also optimise the size and distribution of the crystals.
The results are published in the journal Nano Research: 'III-V semiconductor nanocrystal formation in silicon nanowires via liquid-phase epitaxy' by S. Prucnal et al, DOI: 10.1007/s12274-014-0536-6