Lattice Relaxation and Dislocation Reduction in MBE CdTe(211)B/Ge(211)
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- Badano, G., Gergaud, P., Robin, I.C. et al. Journal of Elec Materi (2010) 39: 908. doi:10.1007/s11664-010-1200-x
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We have used x-ray diffraction to assess the thickness dependence of strain in molecular-beam epitaxial (MBE) CdTe(211)/Ge(211). For 25-nm-thick layers, we find tensile stress of 100 MPa and in-plane strain of ~1.5 × 10−3. This stress relaxes during growth and becomes zero beyond 1 μm. We use the Dunn and Koch formula to estimate the threading dislocation density from the full-width at half-maximum of the (224) rocking curve. We then estimate the annihilation radius of MBE-grown CdTe(211)B/Ge(211) to be ~10 nm. Our layers have etch pit densities between 5 × 107 cm−2 and 5 × 106 cm−2 for a thickness of 10 μm. The lowest densities were obtained by periodic annealing epitaxy. We discuss mechanisms for the saturation of the dislocation density.