Structural features of Sigma=3 and 9, [110] GaAs tilt grain boundaries

The planar density of coincidence sites appears to be high along the observ ed boundary planes for the Sigma = 3 and 9, [110] GaAs tilt grain boundarie s. The polarity in each g-rain on either side of the tilt grain boundaries has been confirmed by direct or indirect methods. The result indicates that a lower number of anti-site type bonds occur along the boundaries compared to when the polarity of one grain is reversed. Based on high-resolution tr ansmission electron microscopy (HRTEM) analysis of several different symmet ric and asymmetric Sigma = 3 and 9, [110] tilt grain boundaries in GaAs, mo dels for the atomic structures of these boundaries have been made for the f irst time; particular atomic arrangements form the structural units of thes e boundaries.