Structure of the metallic Si(001) surface at high temperatures: Synchrotron x-ray scattering measurements

The structure of the metallic Si(001) surface above 900 K was investigated by synchrotron x-ray scattering. Above 900 K, the (2, 1) integer-order surface peak decreases anomalously while the (3/2, 0) reconstruction order peak increases. These results together with the behavior of the crystal truncation rod profile exclude the structural models of the metallic Si(001) surface based on the enhanced Debye-Waller factor and the transition to the symmetrical dimer. The experimental results are explained by the enhanced dynamic step-edge fluctuations induced by the adatom attachments and detachments above 900 K.

Figure 1

Specular CTR profiles measured at 725 K (a) and 970 K (b). The solid lines are fits to the asymmetric dimer model and the dashed lines are fits to the symmetric dimer model.

Figure 2

(a) (2, 1) peak profiles at 1150, 970, and 725 K. The solid lines are the results of the fits to a Lorentzian curve. (b) Temperature dependence of the integrated intensity of the (2, 1) peak. The dashed lines are guide to eye for DW factor.

Figure 3

Schematic diagrams of surface domains with step fluctuations (a) below and (b) above 900 K ($L$ is typical terrace width and $W$ is step meandering width).

Figure 4

(a) (3/2, 0) peak profiles at 1150, 970, and 725 K (the solid lines are fitted by a Lorentzian curve). (b) Temperature dependence of the integrated intensity (1/2, 0) $(○)$ and (3/2, 0) $(●)$ at $l=0.5$ (the dashed lines are guide to eye for DW factor).

Figure 5

FWHMs of (3/2, 0) peak profiles as a function of annealing temperature.