Nano-scale Chemistry of Complex Self-Assembled Nanostructures in Epitaxial SiGe Films

2013 ◽  
Vol 1551 ◽  
pp. 75-80 ◽  
Author(s):  
Prabhu Balasubramanian ◽  
Jerrold A. Floro ◽  
Jennifer L. Gray ◽  
Robert Hull
Keyword(s):  
Self Assembly ◽  
Energy Minimization ◽  
Electron Spectroscopy ◽  
Strain Energy ◽  
Growth Conditions ◽  
Quantum Cellular Automata ◽  
Nano Scale ◽  
Quantum Dot Molecules ◽  
Potential Applications ◽  
Strain Energy Minimization

ABSTRACTHeteroepitaxy of SiGe alloys on Si (001) under certain growth conditions has previously been shown to cause self-assembly of nanostructures called Quantum Dot Molecules, QDMs, where pyramidal pits and 3D islands cooperatively form. QDMs have potential applications to nanologic device architectures such as Quantum Cellular Automata that relies on localization of charges inside islands to create bi-stable logic states. In order to determine the applicability of QDMs to such structures it is necessary to understand the nano-scale chemistry of QDMs because the chemistry affects local bandgap which in turn affects a QDM’s charge confinement property. We investigate the nanoscale chemistry of QDMs in the Si0.7Ge0.3/Si (100) system using Auger Electron Spectroscopy (AES). Our AES analysis indicates that compressively strained QDM pit bases are the most Ge rich regions in a QDM. The segregation of Ge to these locations cannot be explained by strain energy minimization.

Anionopentaaminecobalt(III) complexes with polyamine ligands. XIX. Computer simulated intermediates for dissociative aquation reactions

1984 ◽  
Vol 37 (2) ◽  
pp. 239 ◽  
Author(s):  
DA House ◽  
RGAR Maclagan
Keyword(s):  
Ground State ◽  
Rate Constants ◽  
Energy Minimization ◽  
Strain Energy ◽  
Essential Role ◽  
Energy Difference ◽  
Total Strain Energy ◽  
Dissociative Mechanism ◽  
Approximate Order ◽  
Strain Energy Minimization

Strain energy minimization calculations have been performed for several octahedral chloropenta-amine cobalt(III) complexes with polyamine ligands. Similar calculations on the five-coordinate residue obtained by removal of the chloro ligand allow an estimation of the geometry and energy of a potential intermediate in a chloride release reaction proceeding via a dissociative mechanism. In all cases the five-coordinate residue is less strained than the six-coordinate octahedron and the non-replaced ligands play an essential role in determining the resulting distortion. Thus for the series mer-CoCl(NN)(dien)2+ (NN = en, (NH3)2,tn), the total strain energy difference between the minimized ground state and the minimized five-coordinate residue is 12.2, 18.3 and 25.8 kJ mol-1, respectively. This order is identical (where data are available) to that of the rate constants (and activation energies) for thermal aquation, Hg2+ assisted aquation and mer → fac-dien isomerization in this series. Similar calculations have been performed for a series of trans-CoCl2(N4)+ systems and again the energy differences are in the approximate order of the rates of thermal aquation. In the case of N4 = (NH3)2, the energy difference between trans-and cis-CoCl(NH3)4(OH2)2+ products is about 1 kJ mol-1, the trans-isomer being the more stable.

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