Plasma-assisted molecular beam epitaxy and characterization of (101) on -plane sapphire
Evolution of RHEED observed along the azimuth during growth of on -sapphire. Images (a)–(d) were recorded at , and 3.25, 4.75, and , respectively, after beginning of growth. A transition from a 3D initial surface to a 2D surface was observed.
RHEED images of on -sapphire showing the difference between the (a) azimuth and the (b) ⟨010⟩ azimuth.
HRXRD scan of on -sapphire indicating a phase-pure (101) film. Within the sensitivity of the measurement, there were no other orientations of nor any SnO or Sn detected in the film.
Multiple off-axis XRD scans were used to determine the in-plane epitaxial relationship between the thin film and the -sapphire substrate. The diffraction peak and inclination angle is indicated for each measurement.
(a) Cross-sectional and (b) plan-view TEM images of (101) on -sapphire illustrate dislocations within the film. The dislocation density was as measured from the plan-view image. Dislocation reduction with increasing thickness was observed. AFM section analysis independently verified the surface morphology observed via TEM.
AFM images of the surface for three samples. The film rms for each sample [(a)–(c)] was 15, 21, and , respectively. All three samples were grown with a VI/IV and an oxygen plasma pressure of . Sample (a) was grown with . Samples (b) and (c) were grown with and , respectively. The height scale for each sample [(a)–(c)] was 0–100, 0–130, and . Sample features were elongated along the .
Growth rate and (101) -scan FWHM dependence on substrate temperature. At there was no film growth (not plotted). Samples were grown with a VI/IV at an oxygen plasma pressure of .
(a) Growth rate dependence on Sn flux for three different oxygen plasma pressures. The lines are guides for the eyes. (b) Growth rate dependence on oxygen plasma pressure for different Sn fluxes.
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