Cracking the Si Shell Growth in Hexagonal GaP-Si Core-Shell Nanowires.
Semiconductor nanowires have increased the palette of possible heterostructures thanks to their more effective strain relaxation. Among these, core-shell heterostructures are much more sensitive to strain than axial ones. It is now accepted that the formation of misfit dislocations depends both on the lattice mismatch and relative dimensions of the core and the shell. Here, we show for the first time the existence of a new kind of defect in core-shell nanowires: cracks. These defects do not originate from a lattice mismatch (we demonstrate their appearance in an essentially zero-mismatch system) but from the thermal history during the growth of the nanowires. Crack defects lead to the development of secondary defects, such as type-I1 stacking faults and Frank-type dislocations. These results provide crucial information with important implications for the optimized synthesis of nanowire-based core-shell heterostructures.
†École Polytechnique Fédérale de Lausanne (EPFL), Laboratoire des Matériaux Semiconducteurs (LMSC), 1015 Lausanne, Switzerland.
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Conesa-Boj
‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands.
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Hauge
‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands.|§Philips Innovation Services Eindhoven, High Tech Campus 11, 5656 AE Eindhoven, The Netherlands.
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Verheijen
‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands.
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Assali
‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands.
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Li
‡Department of Applied Physics, TU Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands.|∥Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands.
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Bakkers
†École Polytechnique Fédérale de Lausanne (EPFL), Laboratoire des Matériaux Semiconducteurs (LMSC), 1015 Lausanne, Switzerland.
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Fontcuberta i Morral
Frank-type dislocation; MOVPE; core−shell heterostructures; crack defect; thermal history