Initial growth stage of a highly mismatched strontium film on a hydrogen-terminated silicon (111) surface

Abstract

We report the formation of an atomically abrupt interface without strain in a strontium film using a hydrogen buffer layer on silicon, in spite of large lattice mismatch such as 12%. The onset of the initial growth stage of strontium film with its bulk lattice constant occurs with one atomic layer deposition. The interfacial monoatomic layer of hydrogen together with the first one atomic layer of strontium acts as an effective buffer layer. Our results provide microscopic evidence of heteroepitaxial growth of the strain-free film with the atomically abrupt interface in a highly mismatched system.

Epitaxial growth of largely mismatched crystals on H-terminated Si(111) surfaces

“…The integrated intensity is proportional to the amount of epitaxial Sr crystal in the initial growth stage. After the onset of Sr crystal formation, the intensity increases exactly linearly with the deposited amount, as shown in figure 3(a) [18]. To our surprise, the onset of the initial growth stage of the Sr crystal occurs with one atomic layer deposition, as determined by extrapolating the linear function to zero intensity.…”

“…To our surprise, the onset of the initial growth stage of the Sr crystal occurs with one atomic layer deposition, as determined by extrapolating the linear function to zero intensity. The grain size on the surface can be observed from the full width at half maximum intensity in the RHEED pattern from Si and Sr crystals, as shown in figure 3(b) [18]. At the beginning of the deposited Sr atoms being adsorbed, the streaks originating from the Si surface broaden, which indicates that the ordered Si 1×1 surface area becomes narrower during Sr adsorption.…”

“…This observation suggests that Sr grows epitaxially from the initial stage without disorder on Si. Figure 2(a) shows sequential horizontal profiles of RHEED patterns which are least squares fitted to Lorentzian lines for Sr and Si diffraction streaks in the thickness range of 1.0-2.0 atomic layer deposition [18]. In-plane lattice constants observed from the streak interval originating from Sr and Si respectively are plotted as a function of the growth layer thickness (figure 2(b)) [18].…”

“…This paper reports a Sr epitaxial layer using a monoatomic buffer layer of H grown on Si [15][16][17][18][19][20], in spite of a lattice mismatch of as much as 12%.…”

“…Based on the in situ reflection high-energy electron diffraction (RHEED) method, the onset of the initial stage of crystal Sr growth occurs with only one atomic layer deposition [18]. Real-time measurement of substrate curvature during Sr layer growth on H-terminated Si shows that the lattice mismatch stress and the thickness of the stressed layer of Sr are minimized.…”