Thermodynamic driving force in the formation of hexagonal-diamond Si and Ge nanowires

Growth‐Related Formation Mechanism of I3‐Type Basal Stacking Fault in Epitaxially Grown Hexagonal Ge‐2H

“…[ 47 ] For the {1‐100} surface of hexagonal Si and Ge, it was reported that there are two dangling bonds per unit cell and the number of dangling bonds is not reduced upon reconstruction. [ 48 ] We can speculate that also for the m‐plane, H coverage of dangling bonds may in some way reduce adatom mobility. The observed step‐flow is consistent with the dangling bond diffusion proposed by Kuwahara et al.…”

Impact of Inversion Domain Boundaries on the Electronic Properties of 3C‐SiC

“…In analogy to the GaN case [ 6 ] we have also modeled the so‐called IDB*, as illustrated in the lower panel of Figure 1, by shifting the atomic planes of one of the two domains by in the [001] direction, with a the lattice constant of 3C‐SiC, which is 4.35 Å for our lowest‐energy bulk structure. [ 16 ] Although the GaN case is quite different than the 3C‐SiC one, both concerning the crystal phase (wurtzite vs. zinc blende) and also the orientation of the IDB, the structural configuration of the IDB and IDB* is very similar in the two materials: the IDB shows wrong atomic bonds, i.e., between same atomic species, on the boundary surface; while the IDB* contains fourfold and eightfold rings preventing the wrong bonds of the IDB.…”

“…These latter defects have formation energies of a few tens of meV , even becoming negative at high temperatures. [ 16 ] In contrast, the high formation energy of IDB* confirm that although these defects may be unavoidable when different nucleation domains merge together during the epitaxial growth on planar Si substrates, they can be completely eliminated if off‐cut Si substrates are used. [ 3 ]…”

“…Faulted atomic layers are also evident in both STEM images, as also illustrated in their atomistic models. In particular, a single faulted atomic layer, so‐called intrinsic stacking fault (ISF), [ 16 ] is present in the top structure of Figure 4. Triple faulted atomic layers, forming the so‐called double extrinsic stacking fault (ESFd), are then evident in the bottom STEM image of Figure 4.…”

“…Thus, we cannot calculate the formation energy of a single (111) IDB and hence compare the formation energy of the different IDBs with Si–Si bonds, but with and without SFs. Moreover, the stability of SFs changes with the temperature [ 16 ] and their formation and dynamics during the growth process [ 2 ] may be more important than the ground state energy of the different (111) IDBs to understand the stability of these latter defects. Thus, more specific theoretical investigations are necessary to elucidate this aspect, but the experimental indications restricting the number of structural cases of (111) IDBs appearing in the SiC layers are crucial for our electronic analysis of these defects.…”