TEM analysis of epitaxial semiconductor layers with high stacking fault densities considering artifacts induced by the cross-section geometry

Epitaxial semiconductor layers, in particular II–VI compound semiconductors with the component Se deposited on III–V semiconductor substrates like GaAs or InAs, can contain high densities of stacking faults. CdxMg1−xSe layers with Cd-concentrations x of 93% and 57% on InAs(0 0 1) substrates were investigated as typical representatives of this class of heterostructures. The defect structure of the layers is dominated by a high density of stacking fault (SF) pairs bound by Shockley partial dislocations with Burgers vectors b=16〈1 1 2〉 and a stair-rod dislocation with b=16〈1 1 0〉 at the intersection line of the pairs. Plan-view transmission electron microscopy (TEM) is generally applied to obtain information about the type, density and arrangement of the stacking faults in thin epilayers up to moderate SF densities. Cross-section TEM is more frequently carried out for thick layers and at high SF densities. It will be demonstrated by a detailed analysis of cross-section images that a careful interpretation of the observed SF morphologies is necessary due to artifacts induced by the cross-section geometry.