Defect Engineering in MBE-Grown CdTe Buffer Layers on GaAs (211)B Substrates

• Published in: Journal of electronic materials 2022-09, Vol.51 (9), p.4869-4883
• Main Authors: Pan, W. W., Gu, R. J., Zhang, Z. K., Lei, W., Umana-Membreno, G. A., Smith, D. J., Antoszewski, J., Faraone, L.
• Format: Article
• Language: English
• Subjects: Buffer layers; Cadmium tellurides; Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystal lattices; Dislocation density; Electronics and Microelectronics; Gallium arsenide; Germanium; Infrared detectors; Instrumentation; Lattice matching; Materials Science; Mercury cadmium tellurides; Molecular beam epitaxy; Optical and Electronic Materials; Original Research Article; Silicon substrates; Solid State Physics; Superlattices; Threading dislocations
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-022-09725-1

Demand for high-performance HgCdTe infrared detectors with larger array size and lower cost has fuelled the heteroepitaxial growth of HgCdTe on CdTe buffer layers on lattice-mismatched alternative substrates such as Si, Ge, GaAs and GaSb. However, the resulting high threading dislocation (TD) density in HgCdTe/CdTe limits their ultimate application. Herein, strained CdZnTe/CdTe superlattice layers have been used as dislocation filtering layers (DFL) to reduce the TDs in CdTe buffer layers grown on GaAs (211)B substrates (14.4% lattice-mismatch) by molecular beam epitaxy (MBE). Cross-sectional microstructure characterization indicates that the DFLs suppress the propagation of TDs. For optimal Zn content combined with thermal annealing, the DFLs effectively reduce the defect density of the upper-most CdTe layer from low-10 7 cm −2 to the critical level of below 10 6 cm −2 . In comparison to conventional buffer CdTe layers, the in-plane lattice of the CdTe layers in/near the DFL region is compressively strained, leading to a spread in x-ray double-crystal rocking curve full-width at half-maximum values but better in-plane lattice-matching with HgCdTe. The combined advantages of lower dislocation density and better lattice-matching with HgCdTe indicate that the DFL approach is a promising path towards achieving heteroepitaxy of high-quality HgCdTe on large-area lattice-mismatched substrates for fabricating next-generation infrared detectors.