Determination of structural defects in Hg1-xCdxTe multilayer materials

Lattice mismatch strain, intense strain fields (resulting from the substrate), and gradual and abrupt composition changes at heterojunctions in Hg1-xCdxTe multilayers, were nondestructively investigated by X-ray double crystal diffraction and X-ray topography. Some structural defects at heterojunctions, such as microtwins, stacking faults, mismatch dislocations, and misorientations between multilayer structures Hg1-xCdxTe/CdTe and CdTe/GaAs, were also studied by TEM (transmission electron microscopy). As to the heterojunctions of Hg1-xCdxTe/CdTe/GaAs multilayers grown by MBE (molecular beam epitaxy) method, it is clearly shown that the CdTe buffer layer acts as an effective barrier for the Hg1-xCdxTe epilayer for most structural defects, and the misorientations between multilayer structures Hg1-xCdxTe/CdTe and CdTe/GaAs were found to increase as the lattice mismatch increased. (C) 1997 Elsevier Science B.V.