Early growth of silicon on sapphire. I. Transmission electron microscopy

Abstract

The early growth of Si on (011̄2) ‐oriented sapphire has been examined by transmission electron microscopy. The Si was deposited at 1000 °C by pyrolyzing silane in H₂. The nominal growth rate was 0.4 μm/min. The morphology of the initial Si growth islands was determined after 0.5, 1.0, 2.5, and 3.5 sec of growth. The basic Si orientation is (100) with [01̄1] Si∥[2̄110] Al₂O₃. Extensive faulting and twinning is observed leading to {221} orientations. These defects apparently form at coalescence sites of adjacent islands. Also present are four {110} orientations occuring as twin‐related pairs. The observation of isolated {110} domains indicates that they nucleate on the sapphire independently of the (100) domains. The {110} and (100) domains grow at about the same rate. Eventually, the {110} domains become trapped by the surrounding (100) domains. The volume percentage of the {110} domains is constant with growth time and equals 7% up to coverages of 90%.