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The authors report the growth of semipolar (112¯2) GaN films on nominally on-axis (101¯0) m-plane sapphire substrates using metal organic chemical vapor deposition. High-resolution x-ray diffraction (XRD) results indicate a preferred (112¯2) GaN orientation. Moreover, epitaxial lateral overgrowth (ELO) of GaN was carried out on the (112¯2) oriented GaN templates. When the ELO stripes were aligned along [112¯0]sapphire, the Ga-polar wings were inclined by 32° with respect to the substrate plane with smooth extended nonpolar a-plane GaN surfaces and polar c-plane GaN growth fronts. When compared with the template, the on-axis and off-axis XRD rocking curves indicated significant improvement in the crystalline quality by ELO for this mask orientation (on-axis 1700arcsec for the template, 380arcsec for the ELO sample, when rocked toward the GaN m axis), as verified by transmission electron microscopy (TEM). For growth mask stripes aligned along [0001]sapphire with GaN m-plane as growth fronts, the surface was composed of two {101¯1} planes making a 26° angle with the substrate plane. For this mask orientation XRD and TEM showed no improvement in the crystalline quality by ELO when compared to the non-ELO template.

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We describe a recently discovered stable planar surface of silicon, Si(114). This high-index surface, oriented 19.5 ± away from (001) toward (111), undergoes a 2 3 1 reconstruction. We propose a complete model for the reconstructed surface based on scanning tunneling microscopy images and firstprinciples total-energy calculations. The structure and stability of Si͑114͒-͑2 3 1͒ arises from a balance between surface dangling bond reduction and surface stress relief, and provides a key to understanding the morphology of a family of surfaces oriented between (001) and (114). [S0031-9007(96)00718-1]

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