Electronic and structural properties ofGaAs(100)(2×4)and

Abstract

Electronic and structural properties of GaAs͑100͒͑2 ϫ 4͒, InAs͑100͒͑2 ϫ 4͒, and Sb/ InAs͑100͒͑2 ϫ 4͒ reconstructed surfaces have been studied by synchrotron-radiation photoelectron spectroscopy and scanning tunneling microscopy ͑STM͒. Based on the difference spectrum of As 3d core-level spectra of III-As͑100͒͑2 ϫ 4͒, measured in different surface-sensitivity conditions, as well as the line shape of the As 3d emission from the Sb-induced ͑2 ϫ 4͒ surface, we give evidence that the As 3d spectra of GaAs͑100͒͑2 ϫ 4͒ and InAs͑100͒͑2 ϫ 4͒ consist of two surface-core-level-shifted components. One of them is shifted about 0.2 eV to the lower kinetic energy from the bulk component. On the basis of the relative component intensities, this surface-shifted As 3d component is assigned to the emission from the first-layer As dimers in the established model of the ͑2 ϫ 4͒ surface. The other component, shifted about 0.3 eV to the higher kinetic energy, is connected to the third-layer As-dimer site. The comparison of the core-level results between GaAs͑100͒͑2 ϫ 4͒ and InAs͑100͒ ϫ͑2 ϫ 4͒ suggests that the ␣2 phase, which has one As dimer in both the first and third atomic layers per unit cell, exists on GaAs͑100͒͑2 ϫ 4͒, similarly to the case of InAs͑100͒͑2 ϫ 4͒, as predicted in theory but not observed to date. Furthermore, the STM observation of the GaAs͑100͒͑2 ϫ 4͒␣2 phase is reported.FIG. 1. Some atomic models with the cross sections for the III -V͑100͒͑2 ϫ 4͒ reconstruction: ͑a͒ ␤, ͑b͒ ␣, ͑c͒ ␤2, and ͑d͒ ␣2.PHYSICAL REVIEW B 72, 045321 ͑2005͒

Spatially Localized Formation of InAs Quantum Dots on Shallow Patterns Regardless of Crystallographic Directions

“…The shape transition of the mesa lines, trench, and mesa squares can be attributed to high anisotropic surface diffusion on GaAs (100) substrate. This is due to a corrugated (2 × 4) surface reconstruction [32,33] and preferential adatom incorporation on the sidewalls along [011] directions. During GaAs buffer growth at ∼ 610°C, the natural surface anisotropy on GaAs (100) is mainly attributed to its corrugated (2 × 4) reconstructed surface with dimer rows running along [01-1] direction.…”

“…With corrugated (2 × 4) reconstruction on GaAs (100) surface, the dimer rows run along [01-1] direction, which is generally attributed to high anisotropic adatom surface diffusion. [32,33] When the surface is misoriented along [01-1], ML steps are called "type A" and when the misorientation is along [011], they are called "type B" steps. [34] Sidewalls on both sides of the triangles along [01-1] posses a mixture of both type A and B steps and consequently the relatively low density of QDs on the sidewalls can be a direct result of this mixture.…”

Analytic bond-order potentials for modelling the growth of semiconductor thin films

“…These include the experimentally validated As-terminated b2(2 · 4) [104-106], As-terminated a2(2 · 4) [107], As-rich c(4 · 4) [108,109], and Ga-rich f(4 · 2) [32] surface reconstructions. The surface reconstructions are affected by temperature, vapour composition and deposition rate [31].…”

Tuning the emission profiles of various self-assembled InxGa1−xAs nanostructures by rapid thermal annealing

“…With a ͑2 ϫ 4͒ surface reconstruction, the GaAs surface possesses a highly anisotropic nature induced by the dimer rows running along ͓01− 1͔. [36][37][38] As a result, the anisotropic outward diffusion plays an important role in the formation of nanostructures, and thus, the resulting nanostructures are elongated along ͓01− 1͔. Depending on the thermal energy provided during the capping of 10 ML of GaAs, the degree of diffusion is determined, i.e., more elongation along ͓01− 1͔ with a relatively higher thermal energy.…”