Growth dynamics of selective-area-grown rutile-type SnO₂ on TiO₂ (110) substrate

Abstract

We demonstrated selective-area growth of r-SnO2 on a SiO2-masked r-TiO2 (110) substrate. The heteroepitaxy on a window started with Volmer-Weber mode to grow islands with {100}-, {1-10}-, and {011}-faceted sidewalls, whose growth shapes were consistent with the rutile structure’s equilibrium shape. The islands coalesced each other to make flat (110) top surface on a striped window, and lateral overgrowth started after the complete coverage of the window. Cross-sectional transmission-electron-microscopy observation of the stripe revealed that misfit dislocations propagated perpendicularly to the facet planes by the image force effect and that the dislocation density reduced substantially in the wing regions.

Rutile-type Ge x Sn1−x O2 alloy layers lattice-matched to TiO2 substrates for device applications

“…This growth behavior can be explained by the Frank-van der Merwe mode, where a 2D heteroepitaxial film grows by complete wetting on the substrate with negligibly small lattice mismatches, and is consistent with our lattice-matching epitaxy. The result differs from the growth behavior of r-SnO 2 on r-TiO 2 , which is dominated by the Volmer-Weber mode, 29,35) where a 3D film grows from the initial stage by strong dewetting on the substrate with large lattice mismatches.…”

“…27,28) In our previous study, we conducted selective-area growth of r-SnO 2 on a SiO 2 -masked r-TiO 2 substrate and verified the creation of dislocation-free areas in the lateral overgrown regions. 29) These findings indicate the potential to produce alloy films with reduced dislocation densities through ELO. However, achieving ELO films with high in-plane uniformity would require significant effort.…”

Carrier density control of Sb-doped rutile-type SnO2 thin films and fabrication of a vertical Schottky barrier diode

“…In contrast, the mobility of the film grown at Sb/Sn ratios of 10 −1 mol% exhibits minimal temperature dependence at low temperatures, confirming that the electronic structure of the film is almost degenerate, as mentioned above. Although the film should contain numerous dislocations as previously reported for the r-SnO 2 /r-TiO 2 systems, 29,30) the dislocation scattering becomes less effective for degenerate semiconductors by the screening effect. 31,32) Therefore, the ionized impurity scattering is considered to be the dominant limiting factor of mobility at low temperatures in the film grown at Sb/Sn ratios of 10 −1 mol%.…”