Shear deformation and strain relaxation in HgCdTe on (211) CdZnTe

• Published in: Journal of electronic materials Vol. 29; no. 6; pp. 804 - 808
• Main Authors: Lam, T. T., Moore, C. D., Forrest, R. L., Goorsky, M. S., Johnson, S. M., Leonard, D. B., Strand, T. A., Delyon, T. J., Gorwitz, M. D.
• Format: Journal Article
• Language: English
• Published: Warrendale Springer Nature B.V 01.06.2000
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-000-0228-8

Shear strain is present in Hg sub(0.68)Cd sub(0.32)Te epitaxial layers grown by molecular beam epitaxy on (211)-oriented Cd sub(1-y)Zn sub(y)Te substrates. Differences in the substrate zinc composition led to lattice mismatch between the epitaxial layer and the substrate. The shear strain induced by the mismatch was measured using reciprocal space maps in the symmetric (422) and asymmetric (511) and (333) reflections. In addition, strain relaxation through the formation of misfit dislocations was confirmed using double crystal x-ray topography. Both the shear strain and the misfit dislocation density increased with increasing mismatch between the epitaxial layer and the substrate. Lattice-matched layers were free of misfit dislocations and exhibited triple axis diffraction rocking curve widths of approximately 6 arcsec. The combination of a thick epitaxial layer, a low index substrate, and the potential for lattice mismatch indicates that both shear strains and misfit dislocations must be considered in the structural analysis of HgCdTe/CdZnTe heterostructures.