Energetics of the dihydride phases on the diamond (100) surface

Abstract

It was previously claimed that the herringbone and lean-to dihydride structures possessing a (2ϫ1) symmetry are more stable than other suggested dihydride structures on the C͑100͒ surface, so that the (2ϫ1) patterns frequently observed in low-energy electron diffraction ͑LEED͒ experiments at low temperatures are not sufficient to distinguish between the monohydride and dihydride phases on C͑100͒. To clarify this situation, we investigate the herringbone and lean-to structures using the pseudopotential plane-wave method. Contrary to the claim, we find that these two (2ϫ1):2H structures on C͑100͒ are higher in energy than the canted C(100)-(1ϫ1):2H structure. For completeness, these two structures are also considered for the Si͑100͒ case. Our calculations show that for both the C and Si cases, the canted (100)-(1ϫ1) dihydride phase is the lowest in energy among the dihydride structures considered so far. Therefore, the (2ϫ1) LEED patterns can be assigned to the bare ͑100͒ surface or the monohydride ͑100͒ surface, while the (1ϫ1) symmetry can be associated with the dihydride ͑100͒ surface.

First principles modelling of (100) H‐induced platelets in silicon

“…Theoretical calculations model (100) external surfaces with pairs of internal surfaces in supercells, similar to Figure 1, with very wide separation between surfaces, so that the interaction between the surfaces can be considered negligible. We performed such calculations of widely separated surfaces in order to compare the results with the earlier reports [23,24].…”

“…The models that we adopt for infinite-size (100) platelets are the (100) hydrogenated internal surfaces. External (100) surfaces have been widely studied experimentally [18][19][20][21][22], and a number of theoretical studies exist [23,24]. The principal structures of the (100) hydrogenated internal surfaces are the 1x1 reconstruction and the 2x1 reconstruction of the surface.…”

“…Northrup [23] found the energy difference between the symmetric and canted dihydride 0.18 eV/(1x1) (per pair of H). A more recent study by Hong [24] gave the energy difference 0.16 eV/2H in local density approximation (LDA) calculations and 0.13 eV/2H in generalized gradient approximation (GGA) calculations. Hong considered several other possible canted dihydride structures as well: the "herringbone" and the "lean-to" structures which should have the (2x1) symmetry, and found them to be slightly (0.02-0.03 eV/2H) less stable than the symmetric dihydride, therefore he ruled out the possibility that those structures are observed experimentally as the phase with the (2x1) symmetry.…”

Microstructural study of MBE-grown ZnO film on GaN/sapphire (0001) substrate

“…The insertion of Ga 2 O 3 may have negative effects on the luminescence of devices and result in degradation of the crystal quality of ZnO films compared to ZnO films grown with Znexposure technology [24,25]. However, monoclinic Ga 2 O 3 interface layer has a center of symmetry which leads to the realization of crystal polarity control, i.e.…”

“…However, monoclinic Ga 2 O 3 interface layer has a center of symmetry which leads to the realization of crystal polarity control, i.e. an O-polar (anion-polar) ZnO film can be grown on Ga-polar (cationpolar) GaN by inserting a Ga 2 O 3 layer at the interface [25]. Therefore, this work which demonstrates a closer look of monoclinic Ga 2 O 3 is helpful for us to understand the important role of Ga 2 O 3 in ZnO/GaN heterostructure.…”