An electron microscopy study on the formation mechanism of hillocks on the (100)CdTe/GaAs

Abstract

An electron microscopy study has been performed on the microstructure of (1 0 0)CdTe epitaxial layers, which were grown upon a 4 degrees-off (1 0 0)GaAs substrate by metalorganic chemical vapor deposition. The surface of the epitaxial layer is covered with a large number of elongated pyramidal hillocks along the [0 1 (1) over bar] direction. Their surface density is about 7 x 10(6)/cm(2) and they have various sizes within 2.5 mu m x 6.5 mu m. The hillocks are built up by the propagation of planar defects. Growth-mediated planar defects are responsible for the formation of elongated pyramidal hillocks in relation to the anisotropic distribution of planar defects: planar defects propagated by the growth mechanism are found particularly along the [0 1 (1) over bar] direction. In addition, because the generation of growth-mediated planar defects through deposition errors occurs at any place as well as on substrate surface irregularities, hillocks can have various sizes, (C) 1998 Published by Elsevier Science B.V. All rights reserved.