First-principles simulation of Se and Te adsorbed on GaAs(001)

Abstract

We have studied the adsorption of Se and Te on GaAs͑001͒ using first-principles simulations. For each chalcogen species, 11 structures exhibiting 2ϫ1 reconstruction with varying surface stoichiometry were simulated using a density functional formalism and pseudopotentials, thus yielding absolute surface energies and detailed information about the atomic positions. Our results are discussed in terms of a simple model for heteropolar surfaces and compared to experimental results for these surfaces available from the literature.

Finite temperature studies of Te adsorption on

“…Wiame et al [21] interpreted their STM data in terms of a (2 Â 1) surface reconstruction and the formation of asymmetric Te-Te dimers. The Te adsorbed GaAs(0 0 1) surface is known to show such variable reconstruction with changing temperature [22,23]. The differing reconstruction geometries deduced from different experiments present a puzzling situation.…”

Model study of a surfactant on the GaAs (100) surface

“…Miwa and Ferraz [6] studied the dimer exchange process involved in the growth of a GaAs j InAs interface along the [100] direction. Gundel and Faschinger [7] (GF) determined possible Te sites on GaAs (100). Both of these calculations used the local density approximation [8] of density functional theory [8].…”

“…We used a cluster model approach, because: (1) there still is a controversy about the reconstruction of the GaAs (100) surface when exposed to Te atoms [3,7]; and (2) we intend to explore, without contradicting the experimental conditions, the smallest region on the surface on which the exchange process can occur based on the experimental fact that the exchange process is very efficient [3]. All of our calculations were performed using the same method as in Ref.…”

Reaction path for Te during surfactant-mediated epitaxial growth of GaAs (100)

“…Unfortunately, the reconstruction of the surface used for SME growth of GaAs/Te͑100͒ is still controversial. 4,10,12 Without this crucial piece of information, a slab model for this type of study would cause further controversy.…”

“…On the other hand, it has been determined that the dimerization of Te atoms is not energetically favorable. 10,12 This information, plus the alternating species layers of any zinc-blende ͑100͒ surface, reduces the likelihood of a dimer exchange mechanism for surfactantmediated epitaxial ͑SME͒ growth of GaAs ͑100͒. Unfortunately, the reconstruction of the surface used for SME growth of GaAs/Te͑100͒ is still controversial.…”