Gallium‐rich reconstructions on GaAs(001)

Abstract

Ga-rich reconstructions on GaAs(001) surfaces were prepared by annealing and Ga dosing of Molecular Beam Epitaxy grown samples and analyzed in-situ by Reflectance Anisotropy Spectroscopy and Reflection High-Energy Electron Diffraction. Annealing or dosing gallium above about 800 K invariably results in a (4 Â 2)/c(8 Â 2) reconstruction. Lowering the temperature or annealing below 800 K results in a (2 Â 6)/(3 Â 6) reconstruction. By dosing the (2 Â 6)/(3 Â 6) reconstruction with more than 0.2 monolayer of gallium, it transforms into a (4 Â 6) reconstruction. The observed translational symmetries and measured RAS spectra are compared with results of first-principles calculations. None of the (2 Â 6) structures proposed in the literature is energetically stable. The RAS spectrum calculated for the z(4 Â 2) model resembles reasonably the data measured for the (4 Â 2) surface. The RAS spectra calculated for (2 Â 6) symmetries indicate that mixed Ga-As dimers likely are a structural element of the corresponding surface reconstructions.

Low-temperature atomic assembly of stoichiometric gallium arsenide from equiatomic vapor

“…The dimer/surface binding energy of this transitional bonding state was roughly 70% less than the stable fully adsorbed state, Fig. 3 (6). The existence of such a transitional state during GaAs vapor deposition is consistent with DFT calculations [24].…”

“…The major differences between the methods are the chemical form in which the gallium and arsenic species arrive at the growth surface and the growth surface's atomic structure. The surface atomic structure depends in turn on the growth temperature and the relative concentration of the vapor phase species [5,6].…”

Novel GaAs surface phases via direct control of chemical potential

“…As T is decreased, a transition to the less Ga-rich (6×6) is observed at around 525 °C which is separated by a region of phase coexistence. This is in good agreement with the observations of others who observe these phases at high and low temperatures, respectively, during annealing [1,5,9,11]. We note that the relative intensities of the (6×6) LEED spots without droplets are very different from the (6×6)D phase observed with droplets present.…”

Calculation of reflectance anisotropy for semiconductor surface exploration

“…This model was subsequently confirmed by grazing-incidence X-ray diffraction [32] and is now well accepted in the community. Similarly successful examples for the application of RAS to the surface structure determination include the (001) surfaces of InP [33], GaP [34] and GaAs [35][36][37]. RAS calculations on the IPA level of theory gave indications for the atomic structures of steps on Si(111) [38] and Si(001) surfaces [39] and allowed for the verification of structural models proposed for In nano-wires on Si(111) [40].…”