MBE-growth of CdTe on GaSb substrates: A case study on the influence of substrate quality

I. Madni, W. Lei, Y. L. Ren, J. Antoszewski, L. Faraone

Research output: Contribution to journalArticle

Abstract

CdTe epitaxial layers were grown by MBE on GaSb (211)B substrates from two different suppliers in order to determine the influence of as-received substrate quality on the material quality of subsequently-grown CdTe epilayers. It is observed that GaSb substrates with smooth surface and lower degree of surface roughness can lead to CdTe epilayers with superior material quality, as evidenced by a lower dislocation density, lower etch pit density, lower degree of epilayer surface roughness, narrower XRD FWHM, and lower strain. It is concluded that in comparison to substrates with a relatively smooth surface (RMS surface roughness ∼ 0.62 nm), substrates with a high degree of surface roughness (RMS surface roughness ∼ 2.24 nm) lead to effects that generate misfit dislocations during the MBE growth process. This results in approximately an order of magnitude increase in measured etch pit density (from ∼9 × 105 to 7 × 106 cm−2) and the calculated dislocation density (from 6.51 × 105 to 6.87 × 106 cm−2, as determined from X-ray diffraction reciprocal space mapping), indicating that a smooth substrate surface is critical in achieving high quality CdTe epilayers on GaSb.

Original languageEnglish
Pages (from-to)285-290
Number of pages6
JournalMaterials Chemistry and Physics
Volume214
DOIs
Publication statusPublished - 1 Aug 2018

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Molecular beam epitaxy
Epilayers
surface roughness
Surface roughness
Substrates
Epitaxial layers
Full width at half maximum
Dislocations (crystals)
X ray diffraction
diffraction
x rays

Cite this

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title = "MBE-growth of CdTe on GaSb substrates: A case study on the influence of substrate quality",
abstract = "CdTe epitaxial layers were grown by MBE on GaSb (211)B substrates from two different suppliers in order to determine the influence of as-received substrate quality on the material quality of subsequently-grown CdTe epilayers. It is observed that GaSb substrates with smooth surface and lower degree of surface roughness can lead to CdTe epilayers with superior material quality, as evidenced by a lower dislocation density, lower etch pit density, lower degree of epilayer surface roughness, narrower XRD FWHM, and lower strain. It is concluded that in comparison to substrates with a relatively smooth surface (RMS surface roughness ∼ 0.62 nm), substrates with a high degree of surface roughness (RMS surface roughness ∼ 2.24 nm) lead to effects that generate misfit dislocations during the MBE growth process. This results in approximately an order of magnitude increase in measured etch pit density (from ∼9 × 105 to 7 × 106 cm−2) and the calculated dislocation density (from 6.51 × 105 to 6.87 × 106 cm−2, as determined from X-ray diffraction reciprocal space mapping), indicating that a smooth substrate surface is critical in achieving high quality CdTe epilayers on GaSb.",
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MBE-growth of CdTe on GaSb substrates : A case study on the influence of substrate quality. / Madni, I.; Lei, W.; Ren, Y. L.; Antoszewski, J.; Faraone, L.

In: Materials Chemistry and Physics, Vol. 214, 01.08.2018, p. 285-290.

Research output: Contribution to journalArticle

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AU - Faraone, L.

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