Fabrication of Si/Al2O3/Si silicon on insulator structures grown by ultrahigh-vacuum CVD method

A double-heteroepitaxial S/gamma-Al2O3/Si structure was fabricated for the first time by ultrahigh-vacuum chemical vapor deposition (UHV-CVD). An epitaxial gamma-Al2O3(100) layer was grown on a Si(100) substrate with Al(CH3)(3) and N2O gases at substrate temperatures of 850-1000 degrees C. Subsequently, an epitaxial Si(100) layer was also grown on a gamma-Al2O3(100)/Si(100) substrate by UHV-CVD with Si2H6 gas at substrate temperatures of 750-950 degrees C. These epitaxial layers were characterized by reflection high-energy electron diffraction (RHEED), scanning electron microscopy (SEM), Auger electron spectroscopy (AES), cross-sectional transmission electron microscopy (TEM), Hall effect measurement and ellipsometry. The reflection high-energy electron diffraction of the 5000-Angstrom-thick silicon epitaxial layer indicated streaked 2x1 patterns. From these results, the UHV-CVD method is proven to be an effective method for Al2O3 and silicon growth at low growth temperatures, yielding uniform film thickness and good crystalline quality.