fig2

Figure 2. XRD spectrum and the XRD experimental setup are shown in (A) and (B). (A) XRD from 4 MLs of silicon deposited on the √3 × √3 β-phase of Bi/Si(111) interface; (B) sketch of the XRD experimental setup, allowing the momentum transfer to be sensitive to the film surface structure at ϑi = ϑr, being ϑi and ϑr the incident and reflected scattering angles; α is the in-plane tilt; while ψ is the out of plane tilt. The insert in (A) is the GIXRD spectrum with α = 1.50° and ψ = 2.0°. The GIXRD pattern collected from 4 MLs of Si on the β-phase Si(111)√3 × √3-Bi interface at α = 1.50°, and ψ = 2.0° offset out of the plane is presented in the inset of (A). XRD: X-ray diffraction; ML: monolayer; GIXRD: grazing incidence X-ray diffraction.