Finite temperature studies of Te adsorption on

Abstract

We perform first principles density functional calculations to investigate the adsorption of Te on the Si(0 0 1) surface from low coverage up to a monolayer coverage. At low coverage, a Te atom is adsorbed on top of the Si surface dimer bond. At higher coverages, Te atoms adsorption causes the Si-Si dimer bond to break, lifting the (2 Â 1) reconstruction. We find no evidence of the Te-Te dimer bond formation as a possible source of the (2 Â 1) reconstruction at a monolayer coverage. Finite temperature ab initio molecular dynamics calculations show that Te covered Si(0 0 1) surfaces do not have any definitive reconstruction. Vibrations of the bridged Te atoms in the strongly anharmonic potentials prevent the reconstruction structure from attaining any permanent, two-dimensional periodic geometry. This explains why experiments attempting to find a definite model for the reconstruction reached conflicting conclusions.

Adsorption of Te on Ge(001): Density-functional calculations

“…The structure was relaxed towards its minimum-energy configuration. For Te 2 the relaxed bond length is 2.54 Å, which is somewhat smaller than twice its tetrahedral radius ͑2.64 Å͒ but is in excellent agreement with twice of its normal double bond radius ͑2.54 Å͒ 34 and also in good agreement with the calculated value of 2.56 Å by Sen et al 22 The atomic energy E T ͓Te͔ was taken as half of the total energy of the Te 2 molecule thus calculated. We have calculated the adsorption energy values ͑in eV per Te atom͒ of 3.41, 3.63, and 4.06 for models V, IV, and III, respectively.…”

“…[20][21][22] For the 0.5-ML coverage the adsorption energy of the Te adatom is calculated to be in excess of 2 eV ͑2.8 eV in Ref. 21 and 4.5 eV in Ref.…”

Coverage dependence of the 1-propanol adsorption on theSi(001)surface and fragmentation dynamics

“…In this manner, a large temperature gradient can be avoided. Lattice parameters are expanded according to the temperature under study using the experimental thermal expansion coefficient in order to prevent the lattice from experiencing internal thermal strain 20 . The starting configuration is the physisorbed one I-1, see Fig.…”

Electronic structure of Te- and As-covered Si(211)

“…This absence of Te-Te dimerization is exactly similar to the case of 1-ML Te adsorption on the Si͑001͒ surface. 20 However, in case of the Si͑211͒ surface, the ͑2ϫ1͒ reconstruction of the substrate is retained because the edge Si atoms retain their dimerization. In the optimized structure, the Si-Si dimer distance on the surface is found to be 2.35 Å; and the Si-Te distance is 2.56 Å.…”