Self-energy, adatom

Invoking the Hartree-Fock approximation (HFA) (Salem 1966), means that we can replace Una-a in (4.33) by an averaged self-energy U na-a), whereby an effective adatom level of spin a is defined by2... 

U(na-a) being the averaged self-energy of the adatom, within the HFA. From (5.49), we have... 

At high temperatures, terraces appear to produce most adatoms. Activation energies for mass transfer diffusion are therefore higher than at low temperatures. Evidence for this effect comes from molecular dynamics simnlations for self-diffusion on Lennard-Jones solids [94Sunl] and semi-conductors [96Sunl, 96A111]. The simulations show that the number of adatom-vacancy pairs produced from terraces increases... 

Equation (4.34) is sometimes called the spin-unrestricted HFA, because it allows solutions in which self-consistent adatom orbitals of opposite spin have different energies... 

A method was developed for determining the surface diffusion coefficient and activation energy of Ge adatoms on (001). That is, Ge self-assembled quantum dots which were grown on a relaxed SiGe buffer-layer nucleated preferentially over a network of buried 60° dislocations. The surface sites over the buried dislocations acted as sinks for Ge adatoms. The pre-exponential term in the diffusion constant could also be determined by using Pick s first law, and the observation that the total incident flux of Ge adatoms which impinged on the denuded zones equaled the average rate of volume increase of self-assembled quantum dots over dislocations. The diffusion of Ge adatoms on Si (001) could be described by ... 

A method was developed for determining the surface diffusion coefficient and activation energy of Ge adatoms on (001). That is, Ge self-assembled quantum dots which were grown on a relaxed SiGe buffer-layer nucleated preferentially over a network of buried 60° dislocations. The diffusion of Ge adatoms on Si (001) could be described by ... 

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