TEM analysis of epitaxial semiconductor layers with high stacking fault densities considering artifacts induced by...

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. CdxMg(1-x)Se 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 = 1/6 <1 1 2> and a stair-rod dislocation with b = 1/6 <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.