TY - JOUR A1 - Chee, See Wee A1 - Kammler, Martin A1 - Graham, Jeremy A1 - Gignac, Lynne A1 - Reuter, Mark C. A1 - Hull, Robert A1 - Ross, Frances M. T1 - Directed Self-Assembly of Ge Quantum Dots Using Focused Si2+ Ion Beam Patterning JF - scientific reports N2 - We show that templating a Si surface with a focused beam of Si2+ or Si+ ions can create suitable nucleation sites for the subsequent growth of self-assembled Ge quantum dots by chemical vapor deposition. To determine the mechanism of patterning we use atomic force microscopy to show that, similar to Ga+ patterning, the formation of a surface pit is required to enable control over Ge quantum dot locations. We find that relatively high implantation doses are required to achieve patterning, and these doses lead to amorphization of the substrate. We assess the degree to which the substrate crystallinity can be recovered by subsequent processing. Using in situ transmission electron microscopy heating experiments we find that recrystallization is possible at the growth temperature of the Ge quantum dots, but defects remain that follow the pattern of the initial implantation. We discuss the formation mechanism of the defects and the benefits of using Si ions for patterning both defects and quantum dots on Si substrates. KW - ARRAYS KW - AU KW - DAMAGE KW - GROWTH KW - IMPLANTATION KW - NUCLEATION KW - RECOVERY KW - silicon KW - TECHNOLOGY Y1 - 2018 U6 - https://doi.org/10.1038/s41598-018-27512-z VL - 8 SP - 1 EP - 10 PB - Nature ER - TY - JOUR A1 - Chee, See Wee A1 - Kammler, Martin A1 - Balasubramanian, Prabhu A1 - Reuter, Mark C. A1 - Hull, Robert A1 - Ross, Frances M. T1 - Microstructural changes in silicon induced by patterning with focused ion beams of Ga, Si and Au JF - Ultramicroscopy N2 - We use focused beams of Ga(+), Au(+) and Si(++) ions to induce local microstructural changes in single crystal silicon. The ions were delivered as single spot pulses into thin Si membranes that could subsequently be imaged and annealed in situ in a transmission electron microscope. For each ion, the focused ion beam implantation created an array of amorphous regions in the crystalline membrane. Annealing causes solid phase epitaxial regrowth to take place, but we show that the resulting microstructure depends on the ion species. For Ga(+) and Au(+), precipitates remain after recrystallization, while for Si(++), dislocation loops form around the periphery of each implanted spot. We attribute these loops to defects formed during solid phase epitaxial regrowth, with controlled placement of the loops possible. KW - dislocation engineering KW - focused ion beam KW - In situ electron microscopy KW - solid phase epitaxial regrowth Y1 - 2013 U6 - https://doi.org/10.1016/j.ultramic.2012.07.004 VL - 127 SP - 126 EP - 131 PB - Elsevier ER -