Large thickness-dependent improvement of crystallographic texture of CVD silicon films on R-sapphire

Full CVD Reel‐To‐Reel Process to Obtain Perfectly Oriented Silicon Films on Metal Tapes with Oxide Buffer Layers**

“…At p(SiH 4 ) over 30 mbar (line 3) silicon grows on the substrate epitaxially with a linear dependence of growth rate (GR) on p(SiH 4 ). Noteworthy, the extrapolation of this dependence (line 3) to zero precursor flow fits well with GRp(SiH 4 ) dependence for the deposition of silicon on sapphire discussed in the literature, [9] though the silicon epitaxial growth rate on sapphire is limited to 30 nm min À1 . In comparison, on Y 2 O 3 /YSZ/MgO/Ni(RABiTS) epitaxial growth rate can exceed 100 nm min À1 .…”

“…XRD w-scanning along the Si 311 direction (x ¼ 72.45°) shows eight peaks, which are actually two sets of four 90°-divided peaks each shifted by 36.8°. The first set can be indexed as reflections from (À3-11), (À131), (311), (1-31) sets of planes and the 36.8°-shifted set as reflections from (À311), (131), (3)(4)(5)(6)(7)(8)(9)(10)(11), (À1-31) planes. Such a w-scan structure indicates that the Si film possesses in-plane texture with an average peak FWHM of 5.4.…”

“…Such behavior of epitaxial Si/ sapphire films has been reported in the literature. [9][10][11] Film texture improvement manifests itself by narrowing XRD reflections. Si(311) reflection w scan FWHM (in-plane misorientation) reduces from 6.3°to 4.6°as Si film thickness increases from 200 to 600 nm (Fig.…”

“…Si still localizes on substrate defects, forming islands of Ni-Si, gradually destroying the buffer layer and blocking epitaxial Si growth. Regime 3 occurs when the flow of Si atoms to the substrate is higher than the flow of adatoms [9] Lines correspond to three different deposition regimes, numbered 1, 2, 3 (see text).…”