Towards defect-free epitaxial CdTe and MgCdTe layers grown on InSb (001) substrates

• A dual-chamber molecular beam epitaxy favors high quality growth of II-VI/III-V.
• CdTe epilayers grown at 265 °C had the best structural quality studied by XTEM.
• Monolayer rigid-body displacement present at optimal CdTe/InSb interface studied by aberration-corrected STEM.
• Growth at temperatures of 30 °C higher or lower gave defective epilayers.

A series of three CdTe/MgxCd1−xTe (x~0.24) double heterostructures grown by molecular beam epitaxy on InSb (001) substrates at temperatures in the range of 235–295 °C have been studied using conventional and advanced electron microscopy techniques. Defect analysis based on bright-field electron micrographs indicates that the structure grown at 265 °C has the best structural quality of the series, while structures grown at 30 °C lower or higher temperature show highly defective morphology. Geometric phase analysis of the CdTe/InSb interface for the sample grown at 265 °C reveals minimal interfacial elastic strain, and there is no visible evidence of interfacial defect formation in aberration-corrected electron micrographs of this particular sample. Such high quality CdTe epitaxial layers should provide the basis for applications such as photo-detectors and multi-junction solar cells.