Structural characterization of low-defect-density silicon on sapphire

The structure of (100) silicon on (11̄02) sapphire is discussed for films grown by a special, defect-limiting process. A three-epitaxial-step technique, which utilizes both vapor phase epitaxy and solid phase epitaxy, is employed in the fabrication of low-defect-density films. The effects of different Si⁺ implantation energies and initial Si film thicknesses on the final structure of the film are investigated in order to optimize the electrical characteristics. The improvement in crystalline quality during the solid phase epitaxy step is due to overgrowth of the {221}-oriented microtwins by the [001) Si matrix. Both Rutherford backscattering spectroscopy and cross-sectional transmission electron microscopy are used in the analysis of the structure of these films.