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High resolution electron microscopy and etching study of twins in GaAs

1987; Elsevier BV; Volume: 84; Issue: 3 Linguagem: Inglês

10.1016/0022-0248(87)90278-8

1873-5002

H.W. Zandbergen, J.L. Weyher, J. Van Landuyt,

Quantum Dots Synthesis And Properties

Abstract The combination of etching, photoetching, electron diffraction and high resolution electron microscopy techniques was used to characterize twins in GaAs. These techniques were applied to study (001) oriented samples taken from Si-doped n-type horizontal Bridgman GaAs crystals containing twins. From photoetching and etching it is concluded that the intersection of the twin plane with the (001) plane is parallel to [1 1 0] and that the twin plane is of the [111] type. Selected area electron diffraction and high resolution electron microscopy (HREM) on chemically thinned samples, performed on matrix and twin areas, showed the twin to be a 180° rotation twin or a reflection twin with a (111) composition plane. The model is further confirmed by image calculations. HREM observations also reveal the presence of a thin surface contamination layer of unknown composition on the twin portion of the sample. However this layer did not influence the high resolution images of the GaAs.