Double positioning boundaries on {1¯2•0} and {1¯1•0} planes in wurtzite epilayers that had been grown onto {¯1¯1¯1}B GaP by means of molecular beam epitaxy were studied. Transmission electron microscopic observations demonstrated that the {1¯2•0} boundary which extended a short distance along the c-axis was characterized by a displacement of ½<10•1> and was associated with single growth faults in the basal plane. This boundary formed as a result of island coalescence. On the other hand, the {1¯1•0} boundary originated at the epilayer/substrate interface and ran through the entire epilayer. A g.R analysis, combined with high-resolution electron microscopy, indicated a displacement of 1/3n<11•0> in the basal plane; plus an additional shift of 1/n<00•1> along <00•1>, where n was greater than 3.

Y.Xin, P.D.Brown, C.J.Humphreys, T.S.Cheng, C.T.Foxon: Applied Physics Letters, 1997, 70[10], 1308-10