Reaction pathway for Sb-dimer rotation in conversion ofSb4precursors on Si(001)

Abstract

We report first-principles total-energy calculations that provide detailed reaction pathways for Sb-dimer rotation in evolving processes of Sb4 precursors on the Si(001) surface. We find that the total energy for the Sb dimer perpendicular to the subsurface Si dimers is lower than the parallel dimer by 0.45 eV. We also find a plausible reaction pathway for the Sb-dimer rotation during which only a single dangling bond is created. The calculated activation energy for the rotation is 1.0 eV, indicative that the dirner rotation is rate-determining in the evolving process of Sb4 precursors.

Two-Stage Rotation Mechanism for Group-V Precursor Dissociation on Si(001)

“…AB, AB ! AA) are estimated to be 1.03 for Bi and 0.99 eV for Sb dimers, which are in good agreement with the data reported by Yu et al [14] but lower than 1.28 eV for the concerted rigid rotation pathway [15]. One can see that type B dimers can easily diffuse along the dimer row or rotate to the most stable type A state.…”

“…Experimental evidence suggests splitting and rotation of the adsorbed Sb and Bi tetramers on Si(001) [9,13]. On the theoretical side, previous work has studied the rotation of individual group-V ad-dimers on Si(001) [14,15]. However, the more complicated and important initial stage conversion processes of the experimentally observed precursor tetramer states to ad-dimer states have yet to be explored.…”

Identification of the Si2pSurface Core Level Shifts on theSb/Si(001)−(2×1)Interfac

“…In such an interface structure, the Si substrate atoms show at the most 0.07 Å displacements from their bulk positions and, in particular, the first-layer atoms restore a bulklike geometry. Although this structure agrees with previous theoretical [18,19] and experimental [6] results, an inward relaxation of the first-layer atoms of 0.10 6 0.05 Å was found [20] using x-ray standing waves to characterize the Sb͞Si͑001͒ interface, as also reported in [12]. Moreover, an equilibrium structure showing considerable relaxation has recently been calculated [21], and atomic displacements larger than 0.1 Å have been measured [22] by x-ray diffraction for the first and the deeper Si layers.…”

Adsorption and dynamics of group IV, V atoms and molecular oxygen on semiconductor group IV (0 0 1) surfaces

“…Scanning tunneling microscope (STM) experiments have shown that initially the group V atoms group (Sb and Bi) are adsorbed in the form of Sb 4 tetramers, Bi 4 tetramers and Bi 2 dimers [110][111][112][113]. In the case of Sb 4 on Si(0 0 1) and Ge(0 0 1), the 3D Sb 4 clusters can convert to flat tetramers, which can subsequently [114][115][116][117]. The activation energy for the A → B transformation of the separate Sb ad-dimer on the Si(0 0 1) surface was found to be 1.0 eV [114][115][116][117].…”