Title

High resolution synchrotron extended x-ray absorption fine structure and infrared spectroscopy analysis of MBE grown CdTe/InSb epifilms

Document Type

Article

Publication Date

12-1-2021

Subject Area

ARRAY(0x56094ac20498)

Abstract

Six CdTe thin epifilms were prepared by using molecular beam epitaxy on ion beam cleaned InSb (001) substrates with Tsub temperatures ranging from 25 to 250 °C. Thickness dependent vibrational and structural characteristics are meticulously examined by far-infrared reflectivity (FIR) and high-resolution synchrotron extended x-ray absorption spectroscopy (HR-XAS), respectively. The FIR measured line shapes and optical modes for samples prepared on ion beam cleaned InSb at Tsub ≤ 100 °C revealed abrupt interfaces while noticing segregated Sb atoms and In2Te3-like precipitates at CdTe-InSb interfaces for films grown on ion beam cleaned InSb at Tsub ≥ 230 °C. Our simulated reflectivity results, using a traditional multilayer (ambient/film/substrate) optics methodology, are compared reasonably well with the experimental data. To substantiate the Berreman effect, we have also investigated the transmission and reflectivity spectra of CdTe/InSb epilayers and (CdTe)m/(ZnTe)n/InSb superlattices at oblique incidence (θI = 45°). A clear distinction of the transverse optical (ωTO) phonons in the s-polarization and ωTO and longitudinal optical (ωLO) modes in the p-polarization has established a valuable method of assessing long wavelength optical phonon frequencies in technologically important materials. Comprehensive analysis of HR-XAS results on the structural characteristics of CdTe/InSb epilayers has provided values of bond lengths and coordination numbers in very good agreement with the existing bulk CdTe data.

Publication Title

Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films

Volume

39

Issue

6

Digital Object Identifier (DOI)

10.1116/6.0001145

ISSN

07342101

E-ISSN

15208559

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