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

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Title:	Defect Engineering in MBE-Grown CdTe Buffer Layers on GaAs (211)B Substrates.
Authors:	Pan, W. W.^1,2, Gu, R. J.^1,2, Zhang, Z. K.^1,2, Lei, W.^1,2 wen.lei@uwa.edu.au, Umana-Membreno, G. A.^1,2, Smith, D. J.³, Antoszewski, J.^1,2, Faraone, L.^1,2
Source:	Journal of Electronic Materials. Sep2022, Vol. 51 Issue 9, p4869-4883. 15p.
Subjects:	Buffer layers, Infrared array detectors, Molecular beam epitaxy, Auditing standards, Gallium arsenide, Annealing of metals
Abstract:	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-107 cm−2 to the critical level of below 106 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. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

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Abstract:	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-107 cm−2 to the critical level of below 106 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. [ABSTRACT FROM AUTHOR]
ISSN:	03615235
DOI:	10.1007/s11664-022-09725-1